#include <iostream>
using namespace std;
typedef long long ll;
int main(void){
    int n , x;
    cin >> n >> x;
    ll sum = 0;
    for(int i = 0; i < n; i++){
        int s;
        cin >> s;
        sum += s;
    }
    ll ans = sum - (ll)x * (n - 1);
    cout << ans << endl;
    return 0;
}