题目1015：还是A+B

#include "iostream"
#include "stdio.h"
#include <vector>
#include <cstring>
#include <algorithm>
#include <string>
#include <string.h>
#include <stack>
using namespace std;
//1015
int a,b,k;
int main(){
    //freopen("input.txt","r",stdin);
    while(cin>>a>>b>>k){
        if(a==0&&b==0) break;
        int t=a+b;
        int x=0,y=0;
        while(k--){
            x=x*10+a%10;
            a/=10;
            y=y*10+b%10;
            b/=10;
        }
        if(x==y)    printf("-1\n");
        else        printf("%d\n",t);
     
    }
    return 0;
}
/**************************************************************
    Problem: 1015
    User: cust123
    Language: C++
    Result: Accepted
    Time:0 ms
    Memory:1520 kb
****************************************************************/