#include <bits/stdc++.h>

//#pragma GCC optimize("O3")
//#define int long long

using namespace std;

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;

vector<pair<string, int> > Ans;
vector<int> svs[10];
/*
    0
M
C


    1
C
M


    2
-
C


    3
-
M


    4
C
-


    5
M
-

*/

void goCycle(int start) {
    // Starts at state "start"
    for (int id = start;; id++) {
        if (id % 2 != 0) {
            if (!svs[0].empty()) {
                Ans.push_back({"PICKUP", -1});
                Ans.push_back({"DRIVE", svs[0].back()});
                Ans.push_back({"DROPOFF", -1});
                svs[0].pop_back();
                continue;
            } else if (!svs[5].empty()) {
                Ans.push_back({"PICKUP", -1});
                Ans.push_back({"DRIVE", svs[5].back()});
                Ans.push_back({"DROPOFF", -1});
                svs[5].pop_back();
                break;
            } else {
                break;
            }
        } else {
            if (!svs[1].empty()) {
                Ans.push_back({"PICKUP", -1});
                Ans.push_back({"DRIVE", svs[1].back()});
                Ans.push_back({"DROPOFF", -1});
                svs[1].pop_back();
                continue;
            } else if (!svs[4].empty()) {
                Ans.push_back({"PICKUP", -1});
                Ans.push_back({"DRIVE", svs[4].back()});
                Ans.push_back({"DROPOFF", -1}); 
                svs[4].pop_back();
                break;
            } else {
                break;
            }
        }
    }
}

int n;
string needs, profs;

void solve() {
    for (int i = 0; i < 7; i++) svs[i].clear();
    Ans.clear();
    for (int i = 0; i < n; i++) {
        if (needs[i] == 'M' && profs[i] == 'C')svs[0].push_back(i + 1);
        else if (needs[i] == 'C' && profs[i] == 'M')svs[1].push_back(i + 1);
        else if (needs[i] == '-' && profs[i] == 'C')svs[2].push_back(i + 1);
        else if (needs[i] == '-' && profs[i] == 'M')svs[3].push_back(i + 1);
        else if (needs[i] == 'C' && profs[i] == '-')svs[4].push_back(i + 1);
        else if (needs[i] == 'M' && profs[i] == '-')svs[5].push_back(i + 1);
    }

    if (!svs[2].empty() && !svs[1].empty()) {
        Ans.push_back({"DRIVE", svs[2].back()});
        Ans.push_back({"PICKUP", -1});
        svs[2].pop_back();

        Ans.push_back({"DRIVE", svs[1].back()});
        Ans.push_back({"DROPOFF", -1});
        svs[1].pop_back();
        goCycle(1);
    }

    if (!svs[3].empty() && !svs[0].empty()) {
        Ans.push_back({"DRIVE", svs[3].back()});
        Ans.push_back({"PICKUP", -1});
        svs[3].pop_back();

        Ans.push_back({"DRIVE", svs[0].back()});
        Ans.push_back({"DROPOFF", -1});
        svs[0].pop_back();
        goCycle(0);
    }

    while (!svs[2].empty() && !svs[1].empty()) {
        Ans.push_back({"DRIVE", svs[2].back()});
        Ans.push_back({"PICKUP", -1});
        svs[2].pop_back();

        Ans.push_back({"DRIVE", svs[1].back()});
        Ans.push_back({"DROPOFF", -1});
        svs[1].pop_back();
        goCycle(1);
    }

    while (!svs[3].empty() && !svs[0].empty()) {
        Ans.push_back({"DRIVE", svs[3].back()});
        Ans.push_back({"PICKUP", -1});
        svs[3].pop_back();

        Ans.push_back({"DRIVE", svs[0].back()});
        Ans.push_back({"DROPOFF", -1});
        svs[0].pop_back();
        goCycle(0);
    }




    while (true) {
        if (svs[2].empty() || svs[4].empty())break;
        Ans.push_back({"DRIVE", svs[2].back()});
        Ans.push_back({"PICKUP", -1});
        svs[2].pop_back();

        Ans.push_back({"DRIVE", svs[4].back()});
        Ans.push_back({"DROPOFF", -1});
        svs[4].pop_back();
    }
    while (true) {
        if (svs[2].empty() || svs[1].empty())break;
        Ans.push_back({"DRIVE", svs[2].back()});
        Ans.push_back({"PICKUP", -1});
        svs[2].pop_back();

        Ans.push_back({"DRIVE", svs[1].back()});
        Ans.push_back({"DROPOFF", -1});
        svs[1].pop_back();
    }

    while (true) {
        if (svs[3].empty() || svs[5].empty())break;
        Ans.push_back({"DRIVE", svs[3].back()});
        Ans.push_back({"PICKUP", -1});
        svs[3].pop_back();

        Ans.push_back({"DRIVE", svs[5].back()});
        Ans.push_back({"DROPOFF", -1});
        svs[5].pop_back();
    }
    while (true) {
        if (svs[3].empty() || svs[0].empty())break;
        Ans.push_back({"DRIVE", svs[3].back()});
        Ans.push_back({"PICKUP", -1});
        svs[3].pop_back();

        Ans.push_back({"DRIVE", svs[0].back()});
        Ans.push_back({"DROPOFF", -1});
        svs[0].pop_back();
    }
    // if (!(svs[0].empty() && svs[1].empty() && svs[4].empty() && svs[5].empty())) {
    //     cout << "BUGGGGGGGGGGGG" << endl;
    //     cout << n << endl;
    //     cout << needs << endl;
    //     cout << profs << endl;
    //     exit(1);
    // }
    assert (svs[0].empty() && svs[1].empty() && svs[4].empty() && svs[5].empty());

    cout << Ans.size() << '\n';
    for (auto [i, j] : Ans) {
        cout << i;
        if (j != -1)cout << " " << j;
        cout << '\n';
    }
}

signed main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
    // srand(time(0));
    // for (int id = 1; id <= 1000000; id++) {
    //     n = 20;
    //     profs = "";
    //     needs = "";
    //     while ((int)needs.size() < n) {
    //         int cur = rand() % 3;
    //         if (cur == 0)needs.push_back('-');
    //         if (cur == 1){needs.push_back('M');profs.push_back('M');}
    //         if (cur == 2){needs.push_back('C');profs.push_back('C');}
    //     }
    //     while ((int)profs.size() < n) {
    //         int cur = rand() % 3;
    //         if (cur == 0)profs.push_back('-');
    //         if (cur == 1)profs.push_back('M');
    //         if (cur == 2)profs.push_back('C');
    //     }
    //     random_shuffle(profs.begin(), profs.end());
    //     bool hv = false;
    //     for (int i = 0; i < n; i++) {
    //         if (profs[i] != '-' && needs[i] == '-') {
    //             hv = true;
    //             break;
    //         }
    //     }
    //     if (!hv) continue;
    //     // cout << n << endl;
    //     // cout << needs << endl;
    //     // cout << profs << endl;
        
    //     solve();
    // }

    cin >> n;
    cin >> needs;
    cin >> profs;
    solve();

    return 0;
}

/*
10
CCCC--CMMM
-CCCMM-CMC


6
C--CMM
-MM-CC

*/