#include <bits/stdc++.h>
using namespace std;
long long int power(long long int x, unsigned long long int y,
                    long long int p) {
  long long int res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long int mI(long long int a, long long int m) {
  return power(a, m - 2, m);
}
long long int n, k;
vector<long long int> v;
long long int dp[300001][3][3];
long long int fun(long long int i, long long int s, long long int s1) {
  if (i >= n) return 0;
  if (dp[i][s][s1] != (long long int)1e18) return dp[i][s][s1];
  long long int ans = -1e18;
  if (s == 0) {
    ans = max(ans, v[i] + fun(i + 1, 1, 0));
    ans = max(ans, fun(i + 1, 0, 0));
    ans = max(ans, k * v[i] + fun(i + 1, 1, 1));
  }
  ans = max(ans, fun(i + 1, 2, 2));
  if (s == 1) {
    if (s1 == 0) {
      ans = max(ans, v[i] + fun(i + 1, 1, 0));
      ans = max(ans, k * v[i] + fun(i + 1, 1, 1));
    } else if (s1 == 1) {
      ans = max(ans, k * v[i] + fun(i + 1, 1, 1));
      ans = max(ans, v[i] + fun(i + 1, 1, 2));
    } else if (s1 == 2) {
      ans = max(ans, v[i] + fun(i + 1, 1, 2));
    }
  }
  return dp[i][s][s1] = ans;
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> k;
  v.resize(n);
  for (long long int i = 0; i < n; i++) {
    cin >> v[i];
  }
  for (long long int i = 0; i < 300001; i++) {
    for (long long int j = 0; j < 3; j++) {
      for (long long int k = 0; k < 3; k++) dp[i][j][k] = (long long int)1e18;
    }
  }
  cout << fun(0, 0, 0);
}
