题解 | #还是A+B#

#include<cstdio>
int main(){
	int a, b, k;
	while (scanf("%d %d %d", &a, &b, &k) != EOF){
		if (a == 0&&b==0){
			break;
		}
		int x = a, y = b,i=1;
		for (; i <= k; i++){
			if (a % 10 != b % 10){
				break;
			}
			else{
				a = a / 10;
				b = b / 10;
			}
		}
		if (i > k){
			printf("-1\n");
		}
		else{
			printf("%d\n", x + y);
		}
	}
}