#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int N = 4747;
int n;
string s[2];
// m -> 0, c->1;
int cnt[2];
bool used[N];
vector<string> ans;

int find(string t)
{
	FOR (i, 0, n)
	{
		if (!used[i] && s[0][i] == t[0] && s[1][i] == t[1])
			return i;
	}
	return -1;
}

void solve()
{
	FOR (i, 0, n)
	{
		if (s[0][i] != '-' && s[0][i] != s[1][i])
		{
			int j = s[0][i] == 'M' ? 0 : 1;
			cnt[j]++;
		}
	}
	char c = '-';
	while (cnt[0] + cnt[1] > 0)
	{
		if (c == 'M')
		{
			int x = find("MC");
			if (x == -1)
				x = find("M-");
			assert(x != -1);
			used[x] = 1;
			string res = "DRIVE ";
			res += to_string(x + 1);
			ans.PB(res);
			ans.PB("DROPOFF");
			cnt[0]--;
			if (cnt[1] && s[1][x] == 'C')
			{
				ans.PB("PICKUP");
				c = 'C';
			}
			else
				c = '-';
		}
		else if(c == 'C')
		{
			int x = find("CM");
			if (x == -1)
				x = find("C-");
			assert(x != -1);
			used[x] = 1;
			string res = "DRIVE ";
			res += to_string(x + 1);
			ans.PB(res);
			ans.PB("DROPOFF");
			cnt[1]--;
			if (cnt[0] && s[1][x] == 'M')
			{
				ans.PB("PICKUP");
				c = 'M';
			}
			else
				c = '-';
		}
		else
		{
			int x = find("MC");
			int y = find("-M");
			if (x != -1 && y != -1)
			{
				used[y] = 1;
				string res = "DRIVE ";
				res += to_string(y + 1);
				ans.PB(res);
				ans.PB("PICKUP");
				c = 'M';	
				continue;
			}		
			x = find("CM");
			y = find("-C");
			if (x != -1 && y != -1)
			{
				used[y] = 1;
				string res = "DRIVE ";
				res += to_string(y + 1);
				ans.PB(res);
				ans.PB("PICKUP");
				c = 'C';	
				continue;
			}
			if (cnt[0])
			{
				x = find("-M");
				used[x] = 1;
				string res = "DRIVE ";
				res += to_string(x + 1);
				ans.PB(res);
				ans.PB("PICKUP");
				c = 'M';	
				continue;
			}
			if (cnt[1])
			{
				x = find("-C");
				used[x] = 1;
				string res = "DRIVE ";
				res += to_string(x + 1);
				ans.PB(res);
				ans.PB("PICKUP");
				c = 'C';	
				continue;
			}
		}
	}
	
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n;
	cin >> s[0] >> s[1];
	solve();
	cout << SZ(ans) << '\n';
	for (auto a : ans)
		cout << a << '\n';
	
	return 0;
}