import strutils, sequtils

var
  n = stdin.readLine.parseInt
  mat = newSeqWith(n, newSeqWith(n, ""))
  cnt = newSeqWith(n, 0)

for i in 0.. <n:
  var sp = stdin.readLine.split
  for j, e in sp:
    mat[i][j] = e

for r in 0.. <n:
  for c in 0.. <n:
    if mat[r][c] == "nyanpass":
      cnt[c] += 1

var
  how_many = 0
  res = -1
for i, e in cnt:
  if e == n-1:
    how_many += 1
    res = i+1

echo if how_many != 1: -1 else: res