package main

import (
	"strings"
    "fmt"
    "math"
)

// search needle in haystack
func strStr(haystack string, needle string) int {
    for i := 0; i <= len(haystack) - len(needle); i++ {
        j := 0
        for ; j < len(needle); j++ {
            if haystack[i + j] != needle[j] { break }
        }
        if j == len(needle) { return i }
    }
    return -1
}