/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2021.02.12 21:22:00
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

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