#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

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

int main(){
  ll n,x;
  cin>>n>>x;
  vector<ll> S(n);
  rep(i,n) cin>>S[i];
  
  ll sum=0;
  rep(i,n) sum+=S[i];
  cout<<sum-(n-1)*x<<endl;

  return 0;
}