a = lambda x : 1 if (x == 'nyanpass') or (x == '-') else 0
N = int(input().strip())

lst = []

for x in range(N):
  lst.append([a(i) for i in input().strip().split(' ')])

#print('lst:{}'.format(lst))
lst2 = [0 for i in range(len(lst))]
for i in lst:
  #print('i:{}'.format(i))
  for j in range(len(i)):
    lst2[j] += i[j]

#print('lst2:{}'.format(lst2))
cnt = 0
a = -2
for i in range(len(lst2)):
  #print('i:{} N:{}'.format(i, N))
  if lst2[i] == N:
    if cnt == 0:
      a = i
    else:
      a = -2
    cnt += 1

#print('cnt:{} a:{} N:{}'.format(cnt, a, N))
print(str(a + 1))