addition of three user defined number

source code

void main()
{
int a,b,c,d;
printf("enter first value");
scanf("%d",&a);
printf("enter second value");
scanf("%d",&b);
printf("enter third value");
scanf("%d",&c);
d=a+b+c;
printf("sum of three value is %d",d);
}

output
enter first value 5
enter second value 4
enter third value 1
sum of three value is 10