#include <bits/stdc++.h>
#define pii pair <int, int>

using namespace std;


string a;
string b;
vector<int> x_[2];
vector<int> _x[2]; // C = 0, M = 1
vector<int> xy[2];
struct ura
{
    string a;
    int x;
};
vector<ura>ans;
void solve() {
    int n;
    cin >> n;
    cin >> a;
    a = '#' + a;
    cin >> b;
    b = '#' + b;
    for(int i = 1; i <= n; ++i)
    {
        if(a[i] == b[i])
            continue;
        if(a[i] == '-')
        {
            if(b[i] == 'C')
                _x[0].push_back(i);
            else
                _x[1].push_back(i);
        }
        else if (b[i] == '-')
        {
            if(a[i] == 'C')
                x_[0].push_back(i);
            else
                x_[1].push_back(i);
        }
        else
        {
            if(a[i] == 'C')
                xy[0].push_back(i);
            else
                xy[1].push_back(i);
        }
    }
    int x = 0;
    while(!_x[x].empty())
    {
        int pz = _x[x].back();
        _x[x].pop_back();
        int ceam = x;
        if(!xy[ceam].empty() || !x_[ceam].empty()) 
        {
            ans.push_back({"DRIVE", pz});
            ans.push_back({"PICKUP", 0});
        }
        while(1)
        {
            if(!xy[ceam].empty())
            {
                int npz = xy[ceam].back();
                xy[ceam].pop_back();
                ans.push_back({"DRIVE", npz});
                ans.push_back({"DROPOFF", 0});
                ceam = 1-ceam;
                if(!xy[ceam].empty() || !x_[ceam].empty())
                    ans.push_back({"PICKUP", 0});
            }
            else
                break;
        }
        if(x_[ceam].empty())
        {
            continue;
        }
        assert(!x_[ceam].empty());
        pz = x_[ceam].back();
        ans.push_back({"DRIVE", pz});
        ans.push_back({"DROPOFF", 0});
    }
    x = 1;
    while(!_x[x].empty())
    {
        int pz = _x[x].back();
        _x[x].pop_back();
        int ceam = x;
        if(!xy[ceam].empty() || !x_[ceam].empty()) 
        {
            ans.push_back({"DRIVE", pz});
            ans.push_back({"PICKUP", 0});
        }
        while(1)
        {
            if(!xy[ceam].empty())
            {
                int npz = xy[ceam].back();
                xy[ceam].pop_back();
                ans.push_back({"DRIVE", npz});
                ans.push_back({"DROPOFF", 0});
                ceam = 1-ceam;
                if(!xy[ceam].empty() || !x_[ceam].empty())
                    ans.push_back({"PICKUP", 0});
            }
            else
                break;
        }
        if(x_[ceam].empty())
        {
            continue;
        }
        assert(!x_[ceam].empty());
        pz = x_[ceam].back();
        ans.push_back({"DRIVE", pz});
        ans.push_back({"DROPOFF", 0});
    }

    cout << ans.size() << '\n';
    for(auto i:ans)
    {
        cout << i.a << ' ';
        if(i.x != 0)
            cout << i.x;
        cout<<'\n';
    }
}

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

#ifdef LOCAL
    freopen("test.in", "r", stdin);
    freopen("test.out", "w", stdout);
#else

#endif
    int T = 1;
    //cin >> T;
    while(T--) {
        solve();
    }
    return 0;
}