def main():
    n = int(input())
    l = []
    for i in range(n):
        l.append(input().split(" "))

    ans = []
    for j in range(n):
        num_nyanpass = [l[i][j] for i in range(n)].count("nyanpass")
        if num_nyanpass == n - 1:
            ans.append(j + 1)
    print(ans[0] if len(ans) == 1 else -1)

if __name__ == '__main__':
    main()