import strutils, sequtils, algorithm
proc input: auto = stdin.readLine

let N = input().parseInt
var
  grt = newSeqWith(N, "")
  cnt = newSeqWith(N, 0)

for i in 0 ..< N:
  let A = input().split

  for j, a in A:
    grt[j] &= a
    if i != A.high: grt[j] &= ", "

for i, v in grt:
  cnt[i] = v.count("nyanpass")

if cnt.count(N - 1) == 1:
  echo cnt.find(N - 1) + 1
else:
  echo -1