#include <stdio.h>
int main()
{
    int first reactant,second_reactant)!=1 ||
    if (scanf("%d",&first_reactant) !=1)
    {
        printf("Invalid input");
        return 0;
    }
    if(first_reactant<0 || second_reactant<0)
    {
        printf("Invalid input");
        return 0;
    }
    int total_mass=first_reactant + second_reactant;
    printf("%d",total_mass);
    return 0
}