#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<to;x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

ll B;
int N;
ll C[20];
ll sum;
void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>B>>N;
	ll sum=B;
	FOR(i,N) cin>>C[i], sum+=C[i];
	
	ll mi=1LL<<60;
	FOR(i,N) {
		ll ov=0,fl=0;
		FOR(j,N) if(C[j]>C[i]) ov += C[j]-C[i];
		FOR(j,N) if(C[j]<C[i]) fl += C[i]-C[j];
		if(fl>ov+B) {
			continue;
		}
		else {
			mi=min(mi,fl+ov);
		}
	}
	
	sum=(sum+N-1)/N;
	FOR(i,N) {
		ll ov=0,fl=0;
		FOR(j,N) if(C[j]>sum) ov += C[j]-sum;
		FOR(j,N) if(C[j]<sum) fl += sum-C[j];
		mi=min(mi,fl+ov);
	}
	
	cout<<mi<<endl;
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false);
	FOR(i,argc-1) s+=argv[i+1],s+='\n';
	FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	solve(); return 0;
}