ans=[]
def ILLINRows(N): return [input().split() for i in range(N)]
def transpose(matrix):
    if matrix ==[]:
        return []
    if matrix[0] ==1:
        return list(map(list, zip(matrix)))
    else:
        return list(map(list, zip(*matrix)))
n = int(input())
twoArray=ILLINRows(n)
twoArray=transpose(twoArray)
for i in enumerate(twoArray):
    if i[1].count("nyanpass")==n-1:
        ans.append(i[0]+1)
if len(ans)!=1:
    print(-1)
else:
    print(ans[0])