class Solution {
    public int strStr(String haystack, String needle) {
        if (needle.equals("")) return 0;
        if (haystack.equals("")) return -1;
        int i = 0;
        while (i < haystack.length()) {
            int x = 0;
            int y = i;
            while (y < haystack.length() && x < needle.length() && haystack.charAt(y) == needle.charAt(x)) {
                if ((x+1) >= needle.length()) return i;
                y++;
                x++;
            }
            i++;
        }
        return -1;
    }
}