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

int main (void) {
    unsigned N;
    scanf("%d", &N);

    char A[100][31];
    int s[100] = {0};
    // int *s = calloc(N, (unsigned)sizeof(int));
    int renchon = 0;
    int n;
    int i, j;

    for (i = 0; i < N; i++) {
        for (j = 0; j < N; j++) {
            scanf("%s", A[j]);
            if (strcmp(A[j], "nyanpass") == 0)
                s[j]++;
        }
    }

    for (j = 0; j < N; j++) {
        if (s[j] == N - 1)    renchon++;
        n = j;
    }

    if (renchon != 1) printf("-1");
    else  printf("%d", n + 1);

    // free(s);

    return 0;
}