#include <bits/stdc++.h>

using namespace std;
int n;
char classRoom[2005],teacher[2005];
vector< pair <string,int> > answer;
bool ok[2005];
int numUnsatisfiedClasses[600];
int split[600];
int main() {
    ios_base :: sync_with_stdio(false);
    cin.tie(0);

    cin>>n;
    for (int i=1;i<=n;i++)
    {
        cin>>classRoom[i];
    }
    for (int i=1;i<=n;i++)
    {
        cin>>teacher[i];
        if (classRoom[i]!='-' && teacher[i] != classRoom[i])
        {
            numUnsatisfiedClasses[classRoom[i]]++;
        }
        if (classRoom[i] == teacher[i])
            ok[i]=1;
    }
    char carry = '-';
    while (numUnsatisfiedClasses['C'] > 0 || numUnsatisfiedClasses['M'] > 0)
    {
        memset(split,false,sizeof(split));
        for (int i=1;i<=n;i++)
        {
            if (ok[i] == 1)
                continue;
            if (teacher[i]!='-' && classRoom[i]!='-' && teacher[i] != classRoom[i])
            {
                split[classRoom[i]]=true;
            }
        }
        for (int i=1;i<=n;i++)
        {
            if (ok[i]==1)
                continue;

            if (carry == '-')
            {
                if (teacher[i] != '-' && classRoom[i] == '-' && numUnsatisfiedClasses[teacher[i]]!=0)
                {
                    answer.push_back(make_pair("DRIVE",i));
                    answer.push_back(make_pair("PICKUP",-1));
                    ok[i]=1;
                    carry = teacher[i];
                    teacher[i]='-';
                    break;
                }
            }
            else
            {
                if (classRoom[i] == carry )
                {
                    if (teacher[i] == '-' && split[carry] == true)
                        continue;
                    answer.push_back(make_pair("DRIVE",i));
                    answer.push_back(make_pair("DROPOFF",-1));
                    ok[i]=1;
                    numUnsatisfiedClasses[classRoom[i]]--;
                    carry = '-';
                    if (teacher[i]!='-' && numUnsatisfiedClasses[teacher[i]]!=0)
                    {
                        answer.push_back(make_pair("PICKUP",-1));
                        carry = teacher[i];
                        teacher[i]='-';
                    }
                    break;
                }
            }
        }
    }
    cout<<answer.size()<<'\n';
    for (int i=0;i<answer.size();i++)
    {
        cout<<answer[i].first<<" ";
        if (answer[i].second!=-1)
        {
            cout<<answer[i].second;
        }
        cout<<'\n';
    }
    return 0;
}
/*
 *
4
 -MMC
 M-CM
 */