class Solution {
    public int takeCharacters(String S, int k) {
        char[] s = S.toCharArray();
        int[] cnt = new int[3];
        for(char c: s) cnt[c - 'a'] ++ ;
        if(cnt[0] < k || cnt[1] < k || cnt[2] < k)  return -1;

        int mx = 0, left = 0;
        for(int right = 0; right < s.length; right ++ ){
            int c = s[right] - 'a';
            cnt[c] -- ;
            while(cnt[c] < k){
                cnt[s[left ++ ] - 'a'] ++ ;
            }
            mx = Math.max(mx, right - left + 1);
        }

        return s.length - mx;
    }
}