import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Queue;
import java.util.Scanner;


public class Main {	
	private int n;
	private int how_yes;
	private int[] num;
	private boolean[] bad;
	
	Main(){
		num = new int[10];
		bad = new boolean[10];
	}
	
	public void setN(int n){
		this.n = n;
	}
	
	public void plusHow_yes(){
		this.how_yes++;
	}
	
	public void yes(int[] k){
		for(int i = 0;i < 4;i++){
			num[k[i]]++;
		}
	}
	
	public void no(int[] k){
		for(int i = 0;i < 4;i++){
			bad[k[i]] = true;
		}
	}
	
	public int ans(){
		for(int i = 0;i < 10;i++){
			if(bad[i]) continue;
			if(num[i] == how_yes) return i;
		}
		return -1;
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Main m = new Main();
		int n = sc.nextInt();
		m.setN(n);
		String str;
		int[] k = new int[5];
		for(int i = 0;i < n;i++){
			for(int j = 0;j < 4;j++){
				k[j] = sc.nextInt();
			}
			str = sc.next();
			if(str.equals("YES")){
				m.plusHow_yes();
				m.yes(k);
			}else{
				m.no(k);
			}
		}
		System.out.println(m.ans());
	}
}