N = int(input().strip())

lst = [0 for _ in range(N)]
for i in range(N):
  for n, j in enumerate(input().strip().split(' ')):
    if j == 'nyanpass':
      lst[n] += 1

lst2 = [[n, i] for n, i in enumerate(lst) if i == N - 1]
if len(lst2) == 1:
  print(str(lst2[0][0] + 1))
else:
  print('-1')