#include <stdio.h>
int main(){
    int first reactant;
    int second reactant;
    scanf("%d",&first reactant);
    scanf("%d",&second reactant);
    if((first reactant < 0 ) && (second reactant < 0)){
    printf("Invalid input");
    }
    else{
    printf("%d",first reactant+second reactant); 
    }
    return 0;
}