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

int main(void)
{
    int     N;
    char    A[32];
    int     i, j, s[100] = {};
    int     t;

    scanf("%d", &N);
    for (i = 0; i < N; i++) {
        for (j = 0; j < N; j++) {
            memset(A, '\0', sizeof(A));
            scanf("%s", A);
            if ((strlen(A) == 8) && !strcmp(A, "nyanpass")) {
                s[j]++;
            }
        }
    }

    t = -1;
    for (i = 0; i < N; i++) {
        if (s[i] == (N - 1)) {
            if (t == -1) {
                t = i + 1;
            } else {
                t = -1;
                break;
            }
        }
    }

    printf("%d\n", t);

    return 0;
}