#include <bits/stdc++.h>

using namespace std;

vector<int> m[3][3];

int main() {
    cin.tie(0);
    ios_base::sync_with_stdio(0);
    int n;
    string s1,s0;
    cin>>n>>s1>>s0;
    for(int i=0; i<n; ++i) {
        int a1 = 0;
        if(s1[i]=='M') a1=1;
        else if(s1[i]=='C') a1=2;

        int a0 = 0;
        if(s0[i]=='M') a0=1;
        else if(s0[i]=='C') a0=2;

        if(a0!=a1) {
            m[a0][a1].push_back(i);
        }
    }

    vector<pair<string,int>> ans;
    while(m[1][2].size() || m[2][1].size()) {
        int nb=2,ns=1;
        if(m[1][2].size()>m[2][1].size()) {
            nb=1;ns=2;
        }
        if(!m[ns][0].size()) {
            swap(nb,ns);
        }
        
        ans.push_back({"DRIVE", m[ns][0].back()});
        ans.push_back({"PICKUP", -1});
        m[ns][0].pop_back();

        int nx = ns;
        while(m[3-nx][nx].size()) {
            ans.push_back({"DRIVE", m[3-nx][nx].back()});
            m[3-nx][nx].pop_back();
            ans.push_back({"DROPOFF", -1});
            ans.push_back({"PICKUP", -1});
            nx = 3-nx;
        }
        if(m[0][nx].size()) {
            ans.push_back({"DRIVE", m[0][nx].back()});
            m[0][nx].pop_back();
            ans.push_back({"DROPOFF", -1});
        }
    }
    for(int a=1; a<3; ++a) {
        while(m[0][a].size()) {
            ans.push_back({"DRIVE",m[a][0].back()});
            ans.push_back({"PICKUP",-1});
            m[a][0].pop_back();

            ans.push_back({"DRIVE",m[0][a].back()});
            ans.push_back({"DROPOFF",-1});
            m[0][a].pop_back();
        }
    }
    cout<<ans.size()<<'\n';
    for(auto &x:ans) {
        cout<<x.first<<' ';
        if(x.second!=-1) cout<<x.second+1;
        cout<<'\n';
    }
    
}