#yuki_239

n=int(raw_input())
a=[None for i in xrange(n)]
b=[[None for i in xrange(n)] for j in xrange(n)]
for i in xrange(n):
 a[i]=raw_input().split()
for i in xrange(n):
 for j in xrange(n):
  b[i][j]=a[j][i]
cnt=0
for i in xrange(n):
 if b[i].count('nyanpass')==n-1:
  cnt+=1
  res=i+1
if cnt==1:
 print res
else:
 print -1