import sys
input = sys.stdin.readline
def read_values(): return tuple(map(int, input().split()))
def read_list(): return list(read_values())

def main():
    n = int(input())
    s = input().strip()
    ans = [i + 2 for i in range(len(s)-1) if s[i:i+2] == 'xo']
    print(len(ans))
    print(*ans)
    
if __name__ == "__main__":
    main()