func countBinarySubstrings(s string) int {
	n, cnt := len(s), 0
	if n < 2 {
		return cnt
	}
	for i := 0; i < n-1; i++ {
		if s[i] == s[i+1] {
			continue
		}
		cnt++
		for j := 1; 0 <= i-j && i+j+1 < n; j++ {
			if s[i-j] == s[i] && s[i+j+1] == s[i+1] {
				cnt++
			} else {
				i += j - 1
				break
			}
		}
	}
	return cnt
}