题目1015：还是A+B

#include<stdio.h>

int main()

{

int a,b,f,p,k,A,B;

while(scanf("%d %d %d",&a,&b,&k)!=EOF && (a!=0&&b!=0)) {

p=10; f=0; A=a; B=b;

while(k--){

if((A%p)!=(B%p)){f=1; break;}

else { A=A/10; B=B/10;}

}

if(f==1) printf("%d\n",a+b);

else printf("-1\n");

}

return 0;

}