#include <bits/stdc++.h>
using namespace std;
signed main(){
int x, n;
cin >> x >> n;
priority_queue<int> pq;
priority_queue<int> pq2;
pq2.push(x);
for(int i = 0; i < x; i++){
int st;
cin >> st;
pq.push(-st);
}
int ans = 0;
while(pq.size() > 1){
int num = pq2.top();
ans += num - pq.top();
pq2.push(num - pq.top());
pq2.pop();
pq.pop();
}
cout << ans << endl;
}
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