задача по с++

#include <iostream>

int main(void)
{
std::cout << "first var" << std::endl;
std::cout << "Input a: " ;
double a;
double b;
std::cin >> a;
std::cout << "Input h " << std::endl;

double S = a*h;
std::cout << "Result S = " << S << std::endl;

std::cout << "Second var" << std::endl;
double d1;
double d2;
std::cout << "Input d1" << std::endl;
std::cin >> d1;
std::cout << "Input d2" << std::endl;
std::cin >> d2;
S = (d1+d2)/2;
std::cout << "Result S = " << S << std:: endl;
char c;
std::cin >> c;
return 0;

}