n=int(input())
a=[list(input().split()) for _ in range(n)]
j=[0]*n
for y in range(n):
	for x in range(n):
		if a[y][x]=='nyanpass':
			j[x]+=1
if j.count(n-1)!=1:
	print(-1)
else:
	print(j.index(n-1)+1)