#include <bits/stdc++.h>

using namespace std;

int convert(char c) {
    if (c == '-') return 0;
    else if (c == 'C') return 1;
    else return 2;
}

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int n; cin >> n;
    string need, have;
    cin >> need >> have;
    need = " " + need, have = " " + have;
    vector<int> v[3][3]; // need, have
    for (int i = 1; i <= n; ++i) {
        v[convert(need[i])][convert(have[i])].push_back(i);
    }

    vector<string> solution;
    while (!v[0][1].empty() || !v[0][2].empty()) {
        int n = 0, h = !v[0][1].empty() ? 1 : 2;
        // cout << "START AT " << n << ' ' << h << endl;
        while (true) {
            int id = v[n][h].back();
            v[n][h].pop_back();
            solution.push_back("DRIVE " + to_string(id));
            if (n) solution.push_back("DROPOFF");
            // cout << " at " << n << ' ' << h << endl;

            // going to another one?
            bool cont = false;
            int n2 = h, h2 = 0;
            if (h) {
                if (!v[h][3-h].empty()) h2 = 3-h, cont = true;
                else if (!v[h][0].empty()) h2 = 0, cont = true;
            }
            if (!cont) break;
            solution.push_back("PICKUP");
            n = n2, h = h2;
        }
    }

    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
            if (i && i != j) assert(v[i][j].empty());
        }
    }
    cout << solution.size() << '\n';
    for (string &s : solution) cout << s << '\n';
    return 0;
}