#include <bits/stdc++.h>
using namespace std;

using ll=long long;
//#define int ll
#define rep(i,a,b) for(int i=a;i<(b);i++)
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
using pii=pair<int,int>;
using vi=vector<int>;
#define fi first
#define se second
#define pb push_back
int id(char c) {
    if(c == '-') return 0;
    if(c == 'C') return 1;
    if(c == 'M') return 2;
    assert(0);
}
signed main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    int n;
    cin >> n;
    string S, P;
//    if(local) {
////        for(auto i : S)
//    } else {
        cin >> S >> P;
//    }

    array<array<int, 3>, 3> cnt;
    vector<vector<vector<int>>> edges(3, vector<vector<int>>(3));

    int s = -1;
    int wantM = count(all(S), 'M');
    int wantC = count(all(S), 'C');
    for(auto &i : P) {
        if(i == 'M') {
            if(wantM) wantM--;
            else i = '-';
        }
        if(i == 'C') {
            if(wantC) wantC--;
            else i = '-';
        }
    }
    for(auto &i : cnt) i.fill(0);
    for(int i = 0; i < n; i++) {
        int from = id(S[i]), to = id(P[i]);
        if(from != to) {
            cnt[from][to]++;
            edges[from][to].push_back(i);
            s = from;
        }
    }
    if(s == -1) {
        cout << "0\n";
        return 0;
    }
//    array<int, 3> deg; deg.fill(0);
//    for(int i = 0; i < 3; i++) {
//        for(int j = 0; j < 3; j++) {
//            deg[i] += cnt[i][j];
//            deg[i] -= cnt[j][i];
//        }
//    }
//    int s = 0, t = 0;
//    for(int i = 0; i < 3; i++) {
//        if(deg[i] == 1) s = i;
//        if(deg[i] == -1) t = i;
//    }
//    for(int i = 0; i < 3; i++) {
//        if(i == s || i == t) continue;
//        if(deg[i]) {
//            //wtf
//            assert(0);
//        }
//    }
//    if(s != 0) {
//        //wtf
//        assert(0);
//    }
    vector<pair<string, int>> ops;
    auto get = [&](int u, int v) {
        cnt[u][v]--;
        int t = edges[u][v].back();
        edges[u][v].pop_back();
        return t;
    };
    auto do_edge = [&](int x, int y) -> void {

        while(cnt[x][y] > 1 && cnt[y][x]) {
            ops.push_back({"DRIVE", get(x, y)});
            if(x) ops.push_back({"DROPOFF", 0});
            if(y) ops.push_back({"PICKUP", 0});
            swap(x, y);
            ops.push_back({"DRIVE", get(x, y)});
            if(x) ops.push_back({"DROPOFF", 0});
            if(y) ops.push_back({"PICKUP", 0});
            swap(x, y);
        }

        ops.push_back({"DRIVE", get(x, y)});
        if(x) ops.push_back({"DROPOFF", 0});
        if(y) ops.push_back({"PICKUP", 0});
    };
    auto cycle = [&](int a, int dir) -> bool {
        int x = a;
        int y = (x + dir + 3) % 3;
        int z = (y + dir + 3) % 3;
        if(cnt[x][y] && cnt[y][z] && cnt[z][x]) {
            do_edge(x, y);
            do_edge(y, z);
            do_edge(z, x);
            return true;
        }
        return false;
    };
    while(cycle(s, 1));
    while(cycle(s, 2));

    for(int it = 0; it < 3; it++) {
        for(int i = 0; i < 3; i++) {
            if(cnt[s][i]) {
                do_edge(s, i);
                s = i;
                break;
            }
        }
    }
    for(auto &i : cnt) for(auto &j : i) assert(!j);
    cout << ops.size() << '\n';
    for(auto [s, t] : ops) {
        cout << s;
        if(s == "DRIVE") {
            cout << " " << 1+t << '\n';
        } else cout << '\n';
    }
}