import sequtils, strutils

let n = parseInt readLine stdin
var bools = (1..n).toSeq

for i in 1..n:
  let xs = stdin.readLine.split
  
  for i, a in xs:
    if a == "-": continue
    if a == "nyanpass": continue
    
    bools[i] = -1

bools.keepItIf it > 0

if bools.len == 1:
  echo bools[0]
else:
  echo -1