Thread: how to calculate billion number

i want write program to calculate billion number but when i input a lot of number my program will show negative number

this my code

Code:

int main()
{
    double long a,b,c;
    
    scanf ("%d",&a);
    scanf ("%d",&b);
    c=a+b;
    printf("%d",c);
    
    
getch();
    }

why don't work?

plz help me


ps.sorry my eng is not strong.