C++ :

#include <bits/stdc++.h>
using namespace std;
int main(){
	//freopen("salary.in","r",stdin);
	//freopen("salary.out","w",stdout);
	long long sum=0;
	int n,j=0,i=1;
	cin>>n;
	while(i<=n){
		j+=1;
		for(int k=1;k<=j;k++){
			sum+=j;
			i++;
			if(i>n) break;
		}
			
	}
	cout<<sum;
	return 0;
}

Python :

# coding=utf-8
n=int(input())
s=0
m=1
sumn=0
for i in range(1,n+1,1):
    s=s+1
    if(s>m):
        m=m+1
        s=1
    sumn=sumn+m
print(sumn)