Function main

Codeforces_problems/buttons/solution.cpp:22–38

#include<stdio.h>
int main (){
	long long int n;
	scanf("%lld",&n);
	long long int sum=0;
	int ctr=n-1;
	int temp=0;
	while(ctr>0){
		for(int i=0;i<ctr;i++){
		sum+=temp+1;
	}
		ctr--;
		temp++;
	}
	printf("%lld\n",sum+n);
	
	return 0;
}