class Solution(object):
    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """

        if not needle:
            return 0
        for i in range(len(haystack) - len(needle) + 1):
            if haystack[i] == needle[0]:
                j = 1
                while j < len(needle) and haystack[i + j] == needle[j]:
                    j += 1
                if j == len(needle):
                    return i
        return -1

if __name__ == "__main__":
    answer=Solution()
    print answer.strStr("a","")