from itertools import pairwise


def main():
    N = int(input())
    S = input()
    ans = []
    for idx, (prev, next_) in enumerate(pairwise(S), 2):
        if prev == "x" and next_ == "o":
            ans.append(idx)
    print(len(ans))
    print(*ans)


if __name__ == "__main__":
    main()