def main():
    n = int(input())

    a_lst = [ list(map(str, input().split(' '))) for i in range(n) ]

    aisatsu = 'nyanpass'

    ans_lst = [ 1 for i in range(n) ]

    for i in range(n):
        for j, ele_j in enumerate(a_lst[i]):
            if ele_j != aisatsu and ele_j != '-':
                ans_lst[j] = 0

    ans = -1
    for i, flag in enumerate(ans_lst):
        if flag == 1:
            if ans == -1:
                ans = i+1
            else:
                ans = -1
                break




    print(ans)

if __name__ == '__main__':
    main()