#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#include<stack>
#include<queue>
#include<list>
#include<bitset>

#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007
#define INF 1000000000

using namespace std;


int main(void) {
	int n;
	bool dp[10];

	cin >> n;
	FOR(i, 0, 9) {
		dp[i] = false;
	}
	FOR(i, 1, n) {
		int a, b, c, d;
		string r;
		cin >> a >> b >> c >> d >> r;
		if (r == "NO") {
			dp[a] = true;
			dp[b] = true;
			dp[c] = true;
			dp[d] = true;
		}
	}
	FOR(i, 0, 9) {
		if (dp[i] == false) {
			cout << i << endl;
			break;
		}
	}
	return 0;
}