#include <bits/stdc++.h>
using namespace std;
int n;
long long int gl, t;
long long int dat[100005] = {};
long long int dp[100005] = {};
int main(void) {
  scanf("%d%lld%lld", &n, &gl, &t);
  for (int i = ((int)(1)); i <= ((int)(n)); i++) scanf("%lld", &dat[i]);
  dat[0] = 0;
  dp[0] = 0;
  if (n > 2005) return 0;
  for (int i = ((int)(1)); i <= ((int)(n)); i++) {
    dp[i] = dp[i - 1] + t;
    for (int j = 0; j < ((int)(i)); j++) {
      dp[i] = min(dp[i], dp[j] + max(2 * (dat[i] - dat[j + 1]), t));
    }
  }
  printf("%lld\n", gl + dp[n]);
  return 0;
}
