#include<bits/stdc++.h>
using namespace std;
int main(){
vector<int> arr = {2, 5};
arr.push_back(0);
sort(arr.begin(), arr.end(), [](int& x, int& y){
return x > y;
});
int k = 4;
int ans = 0;
for(int i=0; i<arr.size() && k>0; i++){
if( (arr[i]-arr[i+1])*(i+1) <= k){
ans += (arr[i]*(arr[i]+1)/2 - arr[i+1]*(arr[i+1]+1)/2)*(i+1);
k -= (arr[i]-arr[i+1])*(i+1);
}else if((arr[i]-arr[i+1])*(i+1) > k){
int d = k/(i+1);
int rem = k%(i+1);
int a1 = arr[i], a2 = (arr[i]-d);
ans += ((a1+1)*a1/2 - a2*(a2+1)/2)*(i+1);
ans += rem*a2;
k = 0;
}
}
cout<<ans<<endl;
return 0;
}
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