N = int(input())

isRen = [True]*N
for i in range(N):
    strs = list(input().split())

    for j in range(len(strs)):
        if strs[j] is '-':
            continue
        if strs[j] != 'nyanpass':
            isRen[j] &= False

res = []
for i in range(len(isRen)):
    if isRen[i] :
        res.append(i)

if len(res) != 1:
    print(-1)
else:
    print(res[0]+1)