#include <stdio.h>
#include <stdlib.h>
#include <string.h>



int has_cycle(int matrix[20][20], int n) {
    // TODO: implement this function
    (void) matrix;
    (void) n;
    return 0;
}


int main(void) {
    int n;
    if (scanf("%d", &n) != 1) { return 0; }
    int matrix[20][20] = {{0}};
    char tok[50];
    while (scanf("%49s", tok) == 1) {
        int a, b;
        if (sscanf(tok, "%d-%d", &a, &b) == 2) { matrix[a][b] = 1; }
    }
    printf("%d\n", has_cycle(matrix, n));
    return 0;
}