#include <bits/stdc++.h>

#define all(a) a.begin(),a.end()
#define len(a) (int)(a.size())
#define fir first
#define sec second
#define fi first
#define se second
#define mp make_pair
#define pb push_back

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;

template<typename T>
bool umin(T &a, T b) {
    if (b < a) {
        a = b;
        return 1;
    }
    return 0;
}

template<typename T>
bool umax(T &a, T b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}

#ifdef KIVI
#define DEBUG for (int _____DEBUG=1;_____DEBUG;_____DEBUG=0)
#define LOG(...) prnt(#__VA_ARGS__" ::",__VA_ARGS__)<<endl

template<class ...Ts>
auto &prnt(Ts ...ts) { return ((cerr << ts << " "), ...); }

#else
#define DEBUG while (false)
#define LOG(...)
#endif

const int max_n = -1, inf = 1000111222;

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

vector<vector<int>> ans;

void dfs(int have,int want)
{
    LOG("dfs",have,want);
    ans.back().pb(ids[have][want].back());
    ids[have][want].pop_back();
    if(have == 0) return;
    for (int had=0;had<3;had++){
        if (!ids[had][have].empty()){
            dfs(had,have);
            return;
        }
    }
    LOG("left free",have);
}

int main() {
//    freopen("input.txt","r",stdin);
//    freopen("output.txt","w",stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n;
    cin>>n;
    string want,init;
    cin>>want>>init;
    for (int i=0;i<n;i++){
        if (init[i]!='-' && init[i]==want[i]){
            continue;
        }
        ids[init[i]=='C'?1:(init[i]=='M'?2:0)][want[i]=='C'?1:(want[i]=='M'?2:0)].pb(i);
    }
    while (!ids[1][0].empty()){
        ans.pb({});
        dfs(1,0);
    }
    while (!ids[2][0].empty()){
        ans.pb({});
        dfs(2,0);
    }

    int answer=0;
    for (auto i:ans){
        if (len(i)!=1){
            for (int j=0;j<len(i);j++){
                answer++;
                if (j!=0){
                    answer++;
                }
                if (j!=len(i)-1){
                    answer++;
                }
            }
        }
    }
    cout<<answer<<"\n";
    for (auto i:ans){
        if (len(i)!=1){
            for (int j=0;j<len(i);j++){
                cout<<"DRIVE"<<" "<<i[j]+1<<"\n";
                if (j!=0){
                    cout<<"DROPOFF"<<"\n";
                }
                if (j!=len(i)-1){
                    cout<<"PICKUP"<<"\n";
                }
            }
        }
    }

    exit(0);
}