#include <bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define int long long
using namespace std;

#define maxn 200005
#define inf 0x3f3f3f3f
#define pb push_back
typedef vector<int>vi;

int F(int a,int b){
   // cout<<"a,b "<<a<<" "<<b<<"\n";
    int res=0;
    if(b<=a)res=b*(b-1)/2;
    else if(b>a*2) res=a*a;
    else{
        res=a*a;
        int x=(a*2-b);
       // cout<<"subx "<<x<<"\n";
        res-=x*(x+1)/2;
    }
  //  int res=0;
  //  For(i,1,a)For(j,1,a)if(i+j<=b)res++;
    res-=min(a,b/2);
    return res;
}


signed main()
{
    int a,b,c;cin>>a>>b>>c;
    int res=F(a,min(b,c))+F(b,min(a,c))+F(c,min(a,b));
    res*=8;
    cout<<res;
    return 0;
}
/*
99 89 99
*/