leetcode 2160. Minimum Sum of Four Digit Number After Splitting Digits

class Solution:
    def minimumSum(self, num: int) -> int:
        tmp1=''
        tmp2=''
        numStr=list(str(num))
        numStr.sort()
        for i in range(len(numStr)):
            if i%2==0: tmp1+=numStr[i]
            else :tmp2+=numStr[i]
        return int(tmp1)+int(tmp2)