//判断最后几位是否相同即可
#include<stdio.h>
int main()
{
int a,b,k;
while(scanf("%d %d %d",&a,&b,&k)!=EOF){
if(a==0&&b==0) break;
int m=a,n=b;
int flag=0;
while(k--){
int x=m%10;
m/=10;
int y=n%10;
n/=10;
if(x!=y){
flag=1;
break;
}
}
if(flag)
printf("%d\n",a+b);
else
printf("-1\n");
}
return 0;
}
原文:http://blog.csdn.net/jkxqj/article/details/21820109