def analyze(N, S):
    result_list = []
    for k in range(2, N + 1):
        if S[k-2] == 'x' and S[k-1] == 'o':
            result_list.append(k)
    print(len(result_list))
    if len(result_list) > 0:
        print(" ".join(map(str, result_list)))
N = int(input().strip())
S = input().strip()
analyze(N, S)