Ajutor ...am nevoie repede ...dau coroana .

// 1.
#include <iostream>
int main() {
size_t a, b, c;
std::cin >> a >> b >> c;
std::cout << (a + b + c) / 3.;
}
// 2.
#include <iostream>
int main() {
double x;
std::cin >> x;
std::cout << "Aria: " << x * x << " Perimetru: " << 4. * x;
}