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

int main(void)
{
    
    int all;
    int i, j;
    static char murabito[101][101][31];
    int kaisu;
    int result = -1;
    
    scanf("%d", &all);
    
    for (i = 1; i <= all; i++)
    {
        for (j = 1; j <= all; j++)
        {
            scanf("%s", murabito[i][j]);
        }
    }
    
    for (j = 1; j <= all; j++)
    {
        kaisu = 0;
        for (i = 1; i <= all; i++)
        {
            if (strcmp(murabito[i][j], "nyanpass") == 0)
            {
                kaisu++; /*にゃんぱすと挨拶をした回数*/
            }
        }
        if (kaisu == all - 1)
        {
            if (result == -1)
            {
                result = j;
            }
            else
            {
                result = -1;
                break;
            }
        }
        
    }
    printf("%d\n", result);
    
    return 0;
}