class Solution:
    def shortestWay(self, source: str, target: str) -> int:
        i = 0
        j = 0
        tmp = 0
        count = 0
        while j < len(target):
            tmp = j
            while i < len(source):
                if j >= len(target):
                    break
                if source[i] == target[j]:
                    i += 1
                    j += 1
                else:
                    i += 1
            if j == tmp:
                return -1
            count += 1
            i = 0
        return count