N = int(input())
A = [input().split() for x in range(N)]

def nps(i, j):
    
    if i == N:
        return True
    
    if A[i][j] == '-' or A[i][j] == 'nyanpass':
        return nps(i + 1, j)

    return False

ans = []
for j in range(N):
    if nps(0, j): ans.append(j) 

print(ans[0] + 1 if len(ans) == 1 else -1)