#include <bits/stdc++.h>
namespace ringo {
template <class T>
inline void read(T &x) {
  x = 0;
  register char c = getchar();
  register bool f = 0;
  while (!isdigit(c)) f ^= c == '-', c = getchar();
  while (isdigit(c)) x = x * 10 + c - '0', c = getchar();
  if (f) x = -x;
}
template <class T>
inline void print(T x) {
  if (x < 0) putchar('-'), x = -x;
  if (x > 9) print(x / 10);
  putchar('0' + x % 10);
}
template <class T>
inline void print(T x, char c) {
  print(x), putchar(c);
}
const long long N = 1e5 + 10;
long long n, m, k, ans, a[N], f[N];
void main() {
  memset(f, 0x3f, sizeof(f));
  read(n), read(m), read(k);
  for (long long i = 1; i <= n; i++) read(a[i]);
  f[0] = 0;
  for (long long i = 1; i <= n; i++)
    for (long long j = 0; j < i; j++) {
      f[i] = std::min(f[i],
                      f[j] + a[i] - a[j] + std::max((a[i] - a[j + 1]) << 1, k));
    }
  ans = f[n] + m - a[n];
  print(ans, '\n');
}
}  // namespace ringo
signed main() { return ringo::main(), 0; }
