import datetime
import sys

sys.setrecursionlimit(10 ** 6)
int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]

def main():
    n = int(input())
    aa=[input().split() for _ in range(n)]
    ans=[]
    for i,c in enumerate(zip(*aa),1):
        if c.count("nyanpass")==n-1:
            ans.append(i)
    if len(ans)==1:
        print(ans[0])
    else:
        print(-1)

main()