def main():
    n = int(input())
    d = {}

    for i in range(n):
        d[i] = 0

    for i in range(n):
        l = input().split()
        count = 0
        for e in l:
            if e == "nyanpass":
                d[count] += 1
            count += 1

    ren = []
    for k,v in d.items():
        #print(k,v)
        if v == n - 1:
            ren.append(k)

    ren_size = len(ren)
    if ren_size == 1:
        print(ren[0] + 1)
    else:
        print(-1)


if __name__ == '__main__':
    main()