#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int main() {
	long long n, x, sum = 0;
	cin >> n >> x;
	for (int i = 0; i < n; i++) {
		long long s;
		cin >> s;
		sum += s;
	}
	cout << x - (n * x - sum) << endl;
}