#include<bits/stdc++.h>
using namespace std;
int main(){
    int a,s,d;
    cin>>a>>s>>d;
    if (a<s)swap(a,s);
    if (a<d)swap(a,d);
    if (s<d)swap(s,d);
    cout<<a*s*1+a*d*2+s*d*2;               
	return 0; 
}
/**************************************************************
	Problem: 1340
	User: LYY001
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/