class Solution {
    public int strStr(String haystack, String needle) {
        if(haystack.length()<needle.length()) return -1;
        for(int i=0; i<haystack.length(); i++){
            for(int j=0; ; j++){
                if(i+j==haystack.length()) return -1;
                if(haystack.charAt(i+j) != needle.charAt(j)) break;
                if(j==needle.length()-1) return i;
            }
        }
        return -1;
    }
}