n = int(input())
a = []
for i in range(n):
  a.append(input().split())

renchon = -1
for j in range(n):
  isrenchon = True
  for i in range(n):
    if not (a[i][j] == 'nyanpass' or a[i][j] == '-'):
      isrenchon = False
      break
  if isrenchon:
    if renchon == -1:
      renchon = j + 1
    else:
      renchon = -1
      break
print(renchon)