class Solution {
    
    
    public int strStr(String haystack, String needle) {
    
    
        int len1 = haystack.length();
        int len2 = needle.length();
        int i, j;
        for (i = 0; i <= (len1 - len2); i++) {
    
    
            for (j = 0; j < len2; j++) {
    
    
                if (haystack.charAt(i + j) != needle.charAt(j)) {
    
    
                    break;
                }
            }
            if (len2 == j) {
    
    
                return i;
            }
        }
        return -1;
    }
}