#include <bits/stdc++.h>
using namespace std;
using LL=long long;
#define FOR(i, l, r)for(int i = (l); i<=(r);++i)
#define REP(i, n)FOR(i,0,(n)-1)
#define ssize(x)int(x.size())
#define debug(X...)cerr<<"["#X"]: ", [](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)

auto&operator<<(auto&o,pair<auto, auto>p) {
    return o << "(" << p.first << ", " << p.second << ")";
}
auto operator<<(auto&o, auto x)->decltype(x.end(),o){
    o<<"{";int i=0;for(auto e:x)o<<", "+!i++<<e;return o<<"}";}

int main() {
    int N; cin >> N;

    vector<pair<char, char>> v(N);

    for(int i = 0; i < N; i++) {
        char c; cin >> c;
        v[i].second = c;
    }

    for(int i = 0; i < N; i++) {
        char c; cin >> c;
        v[i].first = c;
    }

    vector<int> chcePusty, CdoM, MdoC, chceM, chceC, nicNaNic;
    for(int i = 0; i < N; i++) {
        if(v[i].first != '-' && v[i].second == '-') chcePusty.push_back(i);
        if(v[i].first == 'M' && v[i].second == 'C') CdoM.push_back(i);
        if(v[i].first == 'C' && v[i].second == 'M') MdoC.push_back(i);
        if(v[i].first == '-' && v[i].second == 'C') chceC.push_back(i);
        if(v[i].first == '-' && v[i].second == 'M') chceM.push_back(i);
        if(v[i].first == '-' && v[i].second == '-') nicNaNic.push_back(i);
    }

    //debug(CdoM);

    int chcePustyI = 0, CdoMI = 0, MdoCI = 0, chceMI = 0, chceCI = 0, nicNaNicI = 0;
    int current = 0;
    queue<string> odp;
    
    while (CdoMI < CdoM.size() || MdoCI < MdoC.size() || chceMI < chceM.size() || chceCI < chceC.size()) {
        // take chcePusty
        if(chcePustyI == chcePusty.size()) {
            break;
        }
        odp.push("DRIVE " + to_string(chcePusty[chcePustyI] + 1) + '\n');
        odp.push("PICKUP\n");
        char motor = v[chcePusty[chcePustyI]].first;
        chcePustyI++;
        //debug(motor);

        // swap a guy
        bool swapsAvailable = true;
        while(swapsAvailable) {
            if(motor == 'C') {
                // look for CdoM
                if(CdoMI != CdoM.size()) {
                    // dropoff guy and swap motor
                    odp.push("DRIVE " + to_string(CdoM[CdoMI++] + 1) + '\n');
                    odp.push("DROPOFF\n");

                    if (chceMI != chceM.size()) {
                        odp.push("PICKUP\n");
                        motor = 'M';
                    } else {
                        motor = '-';
                        break;
                    }
                } else swapsAvailable = false;
            } else {
                // look for MdoC
                if(MdoCI != MdoC.size()) {
                    // dropoff guy and swap motor
                    odp.push("DRIVE " + to_string(MdoC[MdoCI++] + 1) + '\n');
                    odp.push("DROPOFF\n");

                    if (chceCI != chceC.size()) {
                        odp.push("PICKUP\n");
                        motor = 'C';
                    } else {
                        motor = '-';
                        break;
                    }

                } else swapsAvailable = false;
            }
        }

        if (motor == '-') continue;

        // drop off at end M or C
        bool leftAnywhere = false;
        if(motor == 'M') {
            if(chceMI != chceM.size()) {
                odp.push("DRIVE " + to_string(chceM[chceMI++] + 1) + '\n');
                odp.push("DROPOFF\n");
            } else {
                leftAnywhere = true;
            }
        } else {
            if(chceCI != chceC.size()) {
                odp.push("DRIVE " + to_string(chceC[chceCI++] + 1) + '\n');
                odp.push("DROPOFF\n");
            } else {
                leftAnywhere = true;
            }
        }

        if (leftAnywhere) {
            if(nicNaNicI != nicNaNic.size()) {
                odp.push("DRIVE " + to_string(nicNaNic[nicNaNicI++] + 1) + '\n');
                odp.push("DROPOFF\n");
            } else {
                break;
            }
        }
    }

    if(CdoMI == CdoM.size() && MdoCI == MdoC.size() && chceMI == chceM.size() && chceCI == chceC.size()) {
        cout << odp.size() << endl;
        while(!odp.empty()) {
            cout << odp.front();
            odp.pop();
        }
    } else {
        cout << "0" << endl;
    }
}