/*  -*- coding: utf-8 -*-
 *
 * 2856.cc: Window
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100;

/* typedef */

typedef pair<int,int> pii;

/* global variables */

pii ps[MAX_N];

/* subroutines */

/* main */

int main() {
  int n, h, w;
  scanf("%d%d%d", &n, &h, &w);

  for (int i = 0; i < n; i++) {
    int xi;
    scanf("%d", &xi);

    ps[i].first = w * i + ((! (i & 1)) ? xi : -xi);
    ps[i].second = ps[i].first + w;
  }
  sort(ps, ps + n);

  int sum = 0, rp = 0;
  for (int i = 0; i < n; i++) {
    int &li = ps[i].first, &ri = ps[i].second;

    if (rp < li) sum += li - rp;
    if (rp < ri) rp = ri;
  }
  if (rp < n * w) sum += n * w - rp;

  printf("%d\n", sum * h);
  return 0;
}

