#include <bits/stdc++.h>

using namespace std;
const int MAXN = 2010;
int nas[MAXN], pro[MAXN], sled[MAXN], prvi[MAXN];
bool pos[MAXN];
vector<pair<int, int> > p, n;
vector<int> ciklusi;
set<int> boje[MAXN];
vector<pair<string, int> > sol;
void dfs(int node, int idx) {
    pos[node] = true;
    boje[idx].insert(nas[node]);
    if (!pos[sled[node]]) dfs(sled[node], idx);
}

int zajBoja(set<int> &a, set<int> &b) {
    if (a.find(1) != a.end() && b.find(1) != b.end()) return 1;
    if (a.find(2) != a.end() && b.find(2) != b.end()) return 2;
    if (a.find(3) != a.end() && b.find(3) != b.end()) return 3;
    return -1;
}

int main() {
    ios::sync_with_stdio(false);
    int N; cin >> N;
    string nastava; cin >> nastava;
    string profesor; cin >> profesor;
    for (int i = 0; i < N; i++) {
        if (nastava[i] == 'C') {
            nas[i+1] = 1;
        } else if (nastava[i] == 'M') {
            nas[i+1] = 3;
        } else {
            nas[i+1] = 2;
        }
        n.push_back({nas[i+1], i+1});
    }
    for (int i = 0; i < N; i++) {
        if (profesor[i] == 'C') {
            pro[i+1] = 1;
        } else if (profesor[i] == 'M') {
            pro[i+1] = 3;
        } else {
            pro[i+1] = 2;
        }
        p.push_back({pro[i+1], i+1});
    }
    sort(p.begin(), p.end());
    sort(n.begin(), n.end());
    for (int i = 0; i < N; i++) {
        sled[p[i].second] = n[i].second;
    }
    int idx = 0;
    int poc = -1;
    for (int i = 1; i <= N; i++) {
        if (!pos[i]) {
            dfs(i, ++idx);
            if (boje[idx].size() > 1) {
                ciklusi.push_back(idx);
                poc = i;
                prvi[idx] = i;
            }
        }
    }
    if (poc == -1) {
        cout << 0 << endl;
        return 0;
    }

    for (int i = 1; i < ciklusi.size(); i++) {
        int idx1 = ciklusi[i-1], idx2 = ciklusi[i-2];
        int boja = zajBoja(boje[idx1], boje[idx2]);
        
        int tren1 = prvi[idx1];
        int tren2 = prvi[idx2];

        while (nas[sled[tren1]] != boja) {
            tren1 = sled[tren1];
        }
        while (nas[sled[tren2]] != boja) {
            tren2 = sled[tren2];
        }
        int sled1 = sled[tren1];
        int sled2 = sled[tren2];

        sled[tren1] = sled2;
        sled[tren2] = sled1;
    }
    for (int i = 1; i <= N; i++) {
        //cout << "UPAREN " << i << ' ' << sled[i] << endl;
    }
    while (nas[poc] != 2) {
        //cerr << poc << endl;
        poc = sled[poc];
    }
    int tren = poc;
    int havePassenger = false;
    do {
        sol.push_back({"DRIVE", tren});
        if (nas[tren] != 2 || havePassenger) {
            sol.push_back({"DROPOFF", -1});
            havePassenger = 0;
        }
        if (pro[tren] != 2 && sled[tren] != poc) {
            sol.push_back({"PICKUP", -1});
            havePassenger = 1;
        }
        tren = sled[tren];        
    } while (tren != poc);
    cout << sol.size() << '\n';
    for (auto x : sol) {
        if (x.first == "DRIVE") {
            cout << "DRIVE " <<  x.second << '\n';
        } else {
            cout << x.first << '\n';
        }
    }
    return 0;
}