#include <bits/stdc++.h>
using namespace std;
long long dp[100005];
long long pos[100005], n, tt, e;
int main() {
  scanf("%lld %lld %lld", &n, &e, &tt);
  for (int i = 1; i <= n; i++) {
    scanf("%lld", &pos[i]);
  }
  pos[0] = 0;
  dp[0] = 0;
  for (int i = 1; i <= n; i++) {
    dp[i] =
        dp[i - 1] + min(tt + (pos[i] - pos[i - 1]), (pos[i] - pos[i - 1]) * 3);
  }
  printf("%lld", dp[n] + e - pos[n]);
}
