#include <bits/stdc++.h>
using namespace std;
int main(){
  int N, X;
  cin >> N >> X;
  vector<int> S(N);
  for (int i = 0; i < N; i++){
    cin >> S[i];
  }
  long long a = (long long) X * (N - 1);
  long long b = 0;
  for (int i = 0; i < N; i++){
    b += S[i];
  }
  cout << b - a << endl;
}