#include <stdio.h>

int main(){
    int x,y;
    int *ptr_x = &x;
    int *ptr_y = &y;
    int sum;
    
    if(scanf("%d",ptr_x) != 1){
        printf("Invalid input");
        return 0;
    }
    
    if(scanf("%d", ptr_y) != 1)){
        printf("Invalid input");
        return 0;
    }
    
    if(*ptr_x < 0 || *ptr_y < 0){
        printf("Invalid input");
        return 0;
    }
    
    sum = *ptr_x + *ptr_y;
    printf("%d\n",sum);
    
    return 0;
}