#include <bits/stdc++.h>

using namespace std;

int fr[10] = {0};
vector<int> ids[10];
bool first = true;
vector<string> sol;

int _M = 1;
int _C = 2;
int CM = 3;
int MC = 4;
int C_ = 5;
int M_ = 6;

void go(int x)
{
    string aux;
    aux = "DRIVE ";
    aux += to_string(ids[x].back() + 1);
    ids[x].pop_back();
    sol.push_back(aux);
    fr[x]--;

    if (!first)
        sol.push_back("DROPOFF");
    first = false;

    if (x != C_ && x != M_)
        sol.push_back("PICKUP");
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);


    int n;
    cin >> n;
    string needs, gives;
    cin >> needs >> gives;
    for (int i=0;i<n;i++)
    {
        if (needs[i] == '-' && gives[i] == 'C')
        {
            fr[_C]++;
            ids[_C].push_back(i);
        }
        else if (needs[i] == '-' && gives[i] == 'M')
        {
            fr[_M]++;
            ids[_M].push_back(i);
        }
        else if (needs[i] == 'C' && gives[i] == 'M')
        {
            fr[CM]++;
            ids[CM].push_back(i);
        }
        else if (needs[i] == 'M' && gives[i] == 'C')
        {
            fr[MC]++;
            ids[MC].push_back(i);
        }
        else if (needs[i] == 'C' && gives[i] == '-')
        {
            fr[C_]++;
            ids[C_].push_back(i);
        }
        else if (needs[i] == 'M' && gives[i] == '-')
        {
            fr[M_]++;
            ids[M_].push_back(i);
        }
    }

    if (!fr[CM] && !fr[MC] && !fr[C_] && !fr[M_])
    {
        cout << 0 << '\n';
        return 0;
    }

    if (fr[CM] + fr[C_] > fr[MC] + fr[M_])
    {
        go(_C);
        if (fr[CM])
            go(CM);
        while (fr[MC] && fr[CM])
        {
            go(MC);
            go(CM);
        }
        if (fr[M_])
            go(M_);

        while (fr[_M] && fr[M_])
        {
            go(_M);
            go(M_);
        }
        while (fr[CM] && fr[M_])
        {
            go(_C);
            go(CM);
            go(M_);
        }
        while (fr[CM])
        {
            go(_C);
            go(CM);
        }
        while (fr[C_])
        {
            go(_C);
            go(C_);
        }
    }
    else
    {
        go(_M);
        if (fr[MC])
            go(MC);
        while (fr[CM] && fr[MC])
        {
            go(CM);
            go(MC);
        }
        if (fr[C_])
            go(C_);

        while (fr[_C] && fr[C_])
        {
            go(_C);
            go(C_);
        }
        while (fr[C_] && fr[MC])
        {
            go(_M);
            go(MC);
            go(C_);
        }
        while (fr[MC])
        {
            go(_M);
            go(MC);
        }
        while (fr[M_])
        {
            go(_M);
            go(M_);
        }
    }
    if (sol.back() == "PICKUP")
        sol.pop_back();
    cout << sol.size() << '\n';
    for (string& s : sol)
        cout << s << '\n';
    return 0;
}