#include <iostream> #include <math.h> using namespace std; int a, b, c, d; double x; int main() { cout << "Введите A B C D"<<endl; cin >> a>>b>>c>>d; if (a==0 or d==0) { cout<<"\nError"; } else { x = (a*d + b*c)/(a*d); cout <<x; } return 0; }