代码：

#include<bits/stdc++.h>
using namespace std;
int n,m,r[20],h[20],mins=1e9;
int S(){
	int s=0;
	for(int i=1;i<=n;i++){
		s+=r[i]*r[i]-r[i+1]*r[i+1]+2*r[i]*h[i];
	}
	return s;
}
void dfs(int now,int rr,int hh,int s){ 
	if(s<(m-now+2)*(m-now+1)/2) return;
	if(now>m){
		if(s==0) mins=min(mins,S());
		return;
	}
	for(int i=m-now+1;i<=rr;i++){
		for(int j=m-now+1;j<=rr;j++){
			r[now]=i;
			h[now]=j;
			dfs(now+1,i-1,j-1,s-i*i*j);
		}
	}
}
int main(){
	scanf("%d%d",&n,&m);
	int p=sqrt(n);
    dfs(1,p,n,n);
    if(mins==1e9) printf("0");
    else printf("%d",mins);
    return 0;
}