CodeForces 560C Gerald's Hexagon

CodeForces 560C Gerald’s Hexagon

#include <stdio.h>
#include <iostream>
using namespace std;
int main() {
int a[6];
for(int i = 0; i < 6; i++)
cin >> a[i];
long long int s1 = (a[1] + a[2] + a[3]) * (a[3] + a[4] + a[5]);
long long int s2 = a[1] * a[1], s3 = a[3] * a[3], s4 = a[5] * a[5];
cout << s1 - s2 - s3 - s4 << endl;
return 0;
}