#include <iostream>
#include <set>

using namespace std;
using LL = long long;

int main() {
    int N;
    cin >> N;

    set<int> ans;
    for (int i = 0; i <= 9; i++) ans.insert(i);

    int ABCD[4];
    string R;
    for (int i = 0; i < N; i++) {
        for (int i = 0; i < 4; i++) cin >> ABCD[i];
        cin >> R;
        if (R == "YES") {
            set<int> tmp;
            for (int j = 0; j < 4; j++) if (ans.find(ABCD[j]) != ans.end()) tmp.insert(ABCD[j]);
            ans = tmp;
        } else {
            for (int j = 0; j < 4; j++) ans.erase(ABCD[j]);
        }
    }

    cout << *ans.begin() << endl;
}