#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define modulo 1000000007
#define mod(mod_x) ((((long long)mod_x+modulo))%modulo)
#define Inf 1000000001


int main(){
	
	int N;
	cin>>N;
	
	long long X;
	cin>>X;
	
	vector<long long> S(N);
	rep(i,N)scanf("%lld",&S[i]);
	
	long long sum = 0LL;
	rep(i,N)sum += S[i];
	
	sum -= X * (N-1);
	
	cout<<sum<<endl;
	
	return 0;
}