#include <bits/stdc++.h>
using namespace std;
int Gcd(int a, int b) {
  if (b == 0) return a;
  return Gcd(b, a % b);
}
int Lcm(int a, int b) { return a / Gcd(a, b) * b; }
inline int read() {
  int f = 1, x = 0;
  char ch = getchar();
  while (ch > '9' || ch < '0') {
    if (ch == '-') f = -f;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
const int maxn = 1e5 + 10;
int main() {
  long long n = read(), k = read();
  long long cur1 = 0, cur2 = 0, cur = 0, ans = 0;
  for (int i = 0; i < n; i++) {
    long long temp = read();
    cur1 = max(cur1 + temp, 0LL);
    cur2 = max(cur2 + temp * k, cur1);
    cur = max(cur + temp, cur2);
    ans = max(ans, cur);
  }
  cout << ans << endl;
  return 0;
}
