Go: package main

import (
        "fmt"
)

func main() {
        var num int
        for {
                _, err := fmt.Scan(&num)
                if err != nil {
                        break
                } else {
                        fmt.Printf("%d\n", (num*num+num+2)/2)
                }
        }
}

C++: #include <cstdio>
#include <vector>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <sstream>
#include <cmath>
#include <climits>
#include <set>
#include <iostream>
#include <map>
#include <functional>

using namespace std;

#define reep(i,f,n) for(int i=f; i<int(n); ++i)
#define rep(i,n) reep(i,0,n)

typedef vector<int> vi;

int main()
{
	int n;
	while(scanf("%d", &n) != EOF){
		printf("%d\n", n*(n+1)/2+1);
	}

	return 0;
}

C++: #include<bits/stdc++.h>

using namespace std;

int main(){
  int n;
  
  while(cin >> n){
    
    int line[n+1];
    line[0]=1;
    
    for(int i=1;i <= n;i++)
      {
	line[i] = line[i-1] + i;
      }
    cout << line[n] << endl;
  }
  return 0;
}

C++: #include <stdio.h>
int main(){
int n;
while(scanf("%d",&n)!=EOF){
printf("%d\n",(n*(n+1))/2+1);
}
}

C++: #include <stdio.h>

int main(void){
    int lines, areas;

    while (scanf("%d",&lines)!=EOF){
        areas = lines*(lines+1)/2+1;
        printf("%d\n",areas);
    }

    return 0;
}

C++: #include<iostream>
using namespace std;

int main(){
	int i;
	while( cin >> i ){
		int sep=1;
		for( int j=1; j<=i; j++ )	sep += j;
		cout << sep << endl;
	}
	return 0;
}

C++: #include<iostream>
using namespace std;

int main(){
	
	//n = ¼üÌ
	int n;
	
	while(cin >>n){
		if(n == 0) break;
		
		//max = ÅåÌóÔÌ
		int max = 2;
		for(int i = 2; i <= n; i++){
			max += i;
		}
		cout <<max <<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string.h>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<cmath>
#include<utility>
#define ll long long int
#define ld long double
#define INF 1000000000
#define EPS 0.0000000001
#define rep(i,n) for(i=0;i<n;i++)
using namespace std;
typedef pair<int, int> P;

string str;

int main()
{
  int n;

  while(scanf("%d",&n)!=EOF)
    cout<<n*(n+1)/2+1<<endl;
}

C++: #include<iostream>
#include<vector>
using namespace std;

int main(){
  int x;vector<int> anss;
  while(cin>>x){
    anss.push_back(1+0.5*x*(x+1));
  }
  for(int i=0;i<anss.size();i++){
    cout<<anss[i]<<endl;
  }
  return 0;
}

C++: #include<iostream>
using namespace std;
int main(){
	int n;
	while(cin >> n)
		cout << (n*n+n+2)/2 << endl;
}

C++: #include <iostream>
#include <stdio.h>

using namespace std;

int main(void){
  int a_1 = 2;
  int x;
  int s = 0;

  while(scanf("%d", &x) != EOF ){
    if(x == 1){
      printf("%d\n", a_1);
    }else{

      s += a_1;
      for(int i = 2; i <= x; i++){
        s += i;
      }
      printf("%d\n", s);
    }
    s = 0;
  }

  return 0;
}

C++: #include <iostream>

using namespace std;

int main(int argc, char **argv)
{
	int n, r;
	
	while(cin >> n){
		r = 1;
		for(int i = 1; i <= n; i++){
			r += i;
		}
		cout << r << endl;
	}
	
	return 0;
}

C++: main(n){for(;~scanf("%d",&n);)printf("%d\n",1-n*~n/2);}

C++: #include <iostream>
using namespace std;

int main() {
    int n;
    while(cin >> n) {
        cout << n*(n+1)/2+1 << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int main() {
int N; cin >> N; cout << ((N+1)*N/2+1) << endl;
return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

int main() {
    int n;
    while (scanf("%d", &n) != EOF)
        cout << n * (n + 1) / 2 + 1 << endl;

    return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;
using ll = long long;
using pii = pair<int, int>;

int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(10);
  
  int n;
  while (cin >> n) {
    cout << n * (n + 1) / 2 + 1 << endl;
  }

  return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <string>
#include <math.h>
#include <functional>
#include <algorithm>
#include <utility>

typedef long long Int;
#define REP(i,n) for(int i = 0 ; i < n ; ++i)
#define REPS(a,i,n) for(int i = a ; i < n ; ++i)
using namespace std;

int tile[20][20];

int func(int n){
	int a = 0;
	REP(i, n + 1){
		a += i;
	}
	return a;
}

int main(){
	int n;
	while (cin >> n){
		if (n == 1)
			cout << 2 << endl;
		else
			cout << func(n - 2) + 2 * n << endl;
	}

	return 0;
}

C++: #include <iostream>

using namespace std;

int main(void) {
	// n+1本目の直線は最大n個の直線と交差し、交差数＋1個の領域を分割する
	// An+1 = An + n + 1, A1 = 2
	// An = 2 + Σ(k+1)
	// An = (n^2 + n + 2) / 2

	int n;

	while (cin >> n) {
		cout << (n * n + n + 2) / 2 << endl;
	}
}

C++: #include <iostream>
using namespace std;

int main(){

  int a[10001] ;
  a[1] = 2;
  for(int i=2;i<=10000;i++) a[i] = a[i-1] + i;

  int n
  while(cin >> n){
  cout << a[n] << endl;
  }
  
  return 0;
}

C++: #include<iostream>
#include<iomanip>
#include<string>
#include<algorithm>
#include<cmath>
using namespace std;
int main(){
    int n;
    while(cin>>n){
        int ans=1;
        for(int i=1;i<n+1;i++){
            ans+=i;
        }
        cout<<ans<<endl;
    }
    return 0;
}

C++: #include<iostream>
using namespace std;

void solve(int ans[10001]){
    for(int i=2; i<10001; i++){
        ans[i]=ans[i-1]+i;
    }
}

int main()
{
    int n,ans[10001];
    ans[1]=2;
    solve(ans);
    while(cin>>n,!cin.eof()){
        cout<<ans[n]<<endl;
    }
    return 0;
}

C++: #include <iostream>
#include <queue>
#include <stack>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <string>
#include <cmath>
#include <complex>
#include <map>
using namespace std;

#define rep(i,n) for(int i=0;i<int(n);++i)
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define EPS 1e-8

static const double PI=6*asin(0.5);
typedef complex<double> P;
typedef long long ll;


//1=2
//2=4
//3=6+1=7
//4=8+3=11
//5=10+6=16
//6=12+10=22

int n;
vector<ll> a;
int main(){
	a.PB(0);
	a.PB(0);
	a.PB(0);
	a.PB(1);
	a.PB(3);
	rep(i,10000) a.PB(a[a.size()-1]+a.size()-2);
	//rep(i,30) cout<<a[i]<<endl;
	while(cin>>n){
		ll res=2*n;
		res+=a[n];
		//cout<<a[n]<<endl<<endl;
		cout<<res<<endl;
	}
	return 0;
}

C++: #include <iostream>

using namespace std;

void solve()
{
	int n;
	while(cin >> n)
	{
		cout << n * (n + 1) / 2 + 1 << endl;
	}
}

int main()
{
	solve();
	return(0);
}

C++: #include <iostream>
using namespace std;

int main(){
    int n;
    while(cin >> n){
        cout << 1+n*(n+1)/2 << endl;
    }
    return 0;
}

C++: #include <iostream>
using namespace std;

int main() {
  int n;
  while(cin >> n) cout << n*(n+1)/2+1 << endl;
  return 0;
}

C++: #include <iostream>
using namespace std;

int main() {
  int n;
  while(cin>>n) {
    cout << 1+n*(n+1)/2 << endl;
  }
}