#include<stdio.h>
int main()
{
    int r1,r2;
    if(scanf("%d %d",&r1,&r2)!=2){
        printf("Invalid input");
        return 0;
    }
    if(r1 < 0 || r2 < 0)
    printf("Invalid input");
    else
    printf("%D",r1+r2);
    return 0;
}