#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>

int main() {
  ll n, x;
  cin >> n >> x;
  ll sum = 0;
  rep(i,n) {
    ll s;
    cin >> s;
    sum += s;
  }
  ll ans = sum - (n-1)*x;
  cout << ans << endl;


}