1.4

#include <iostream>
#include <math.h>
using namespace std;
int x1, x2, x3;
double y;

int main() {
    cout << "Введите X1, X2, X3"<<endl;
    cin>> x1 >> x2 >> x3;
    y = x1*x2 + x1*x3 + x2*x3;
    cout << y;
    return 0;
}