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

int main()
{
	long long N, X;
	cin >> N >> X;
	long long s = 0;
	for( int i = 0; i < N; i++ ) {
		int S;
		cin >> S;
		s += S;
	}

	int ans = s - X * (N - 1);

	cout << ans << endl;
}