#include <stdio.h> #include <iostream> #include <vector> #include <map> #include <queue> #include <algorithm> #include <set> #include <math.h> #include <string> #include <stdlib.h> #include <string.h> #include <iomanip> using namespace std; typedef pair<int, int> pii; #define ll long long #define INF 1e9 int main() { // freopen("C:\\in.txt", "r", stdin); int a,b,c,d; int x; int n=4; vector<int> v; while(n--){ scanf("%d", &x); v.push_back(x); } sort(v.rbegin(), v.rend()); cout << v[0] * v[1] + v[2]*v[3] << endl; return 0; }