#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define endl '\n'
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rep2(i,a,b) for(int i=int(a);i<int(b);i++)
#define pb emplace_back
#define all(x) (x).begin(),(x).end()
int mod=1e9+7;
int mod2=998244353;
const int INF=1e9;
//g++ -std=c++11 a.cpp

signed main(){
	ll n,h,w;
    cin>>n>>h>>w;
    ll ans=0;
    rep(i,n/2){
        ll a,b;
        cin>>a>>b;
        b=2*w-b-w;
        //cout<<a<<" "<<b<<endl;
        ans+=min(a,b);
        ans+=2*w-max(a+w,b+w);
    }
    cout<<ans*h<<endl;
}

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