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)
                }
        }
}

Python: # coding=utf-8

###
### for python program
###

import sys
import math

# math class
class mymath:
    ### pi
    pi = 3.14159265358979323846264338

    ### Prime Number
    def pnum_eratosthenes(self, n):
        ptable = [0 for i in range(n+1)]
        plist = []

        for i in range(2, n+1):
            if ptable[i]==0:
                plist.append(i)
                for j in range(i+i, n+1, i):
                    ptable[j] = 1
        return plist

    def pnum_check(self, n):
        if (n==1):
            return False
        elif (n==2):
            return True
        else:
            for x in range(2,n):
                if(n % x==0):
                    return False
            return True

    ### GCD
    def gcd(self, a, b):
        if b == 0:
            return a
        return self.gcd(b, a%b)

    ### LCM
    def lcm(self, a, b):
        return (a*b)//self.gcd(a,b)

    ### Mat Multiplication
    def mul(self, A, B):
        ans = []
        for a in A:
            c = 0
            for j, row in enumerate(a):
                c += row*B[j]
            ans.append(c)
        return ans

mymath = mymath()

### output class
class output:
    ### list
    def list(self, l):
        l = list(l)
        #print(" ", end="")
        for i, num in enumerate(l):
            print(num, end="")
            if i != len(l)-1:
                print(" ", end="")
        print()

output = output()

### input sample
#i = input()
#N = int(input())
#A, B, C = [x for x in input().split()]
#N, K = [int(x) for x in input().split()]
#inlist = [int(w) for w in input().split()]

#R = float(input())
#A.append(list(map(int,input().split())))

#for line in sys.stdin.readlines():
#    x, y = [int(temp) for temp in line.split()]

#abc list
#abc = [chr(ord('a') + i) for i in range(26)]

### output sample
# print("{0} {1} {2:.5f}".format(A//B, A%B, A/B))
# print("{0:.6f} {1:.6f}".format(R*R*math.pi,R*2*math.pi))
# print(" {}".format(i), end="")

# def printA(A):
#     for i, n in enumerate(A):
#         print(n, end='')
#         if i != N-1:
#             print(' ', end='')
#     print()

# リスト内包表記 ifあり
# [x-k if x != 0 else x for x in C]

# ソート
# N = N.sort()

# 10000個の素数リスト
# P = mymath.pnum_eratosthenes(105000)

def is_integer(n):
    try:
        float(n)
    except ValueError:
        return False
    else:
        return float(n).is_integer()

def dist(A, B):
    d = 0
    for i in range(len(A)):
        d += (A[i]-B[i])**2            
    d = d**(1/2)
    return d

def get_input():
    N = []
    while True:
        try:
            #N.append(input())
            N.append(int(input()))
            #N.append(float(input()))
        except EOFError:
            break
    return N

N = get_input()

for n in N:
    ans = 2
    for i in range(2,n+1):
        ans += i
    print(ans)

Python: while True:
	try:
		x = int(input())
		print(int((x**2 + x + 2) / 2))
	except:
		break

Python: while True:
    try:
        a = int(input())
        print(str(int(((a * a) + a + 2) / 2)))
    except EOFError:
        break

Python: while True:
    try:
        n = int(input())
        print((n**2 + n + 2)//2)
    except:
        break

Python: import sys
for e in sys.stdin:e=int(e);print(e*(e+1)//2+1)

Python: import sys
lc=lambda n:int((n**2+n+2)/2)
[print(i) for i in [lc(int(j)) for j in sts.stdin]]

Python: while 1:
    try:
        n = int(input())
        print(int(2+(n - 1) * (n + 2)*0.5))
    except:
        break

Python: while True:
    try:
        l= int(input())
    except:
        break
    print((l**2+l+2)//2)

Python: import sys
f = sys.stdin

for n in f:
    n = int(n)
    print(n * (n + 1) // 2 + 1)

Python: import sys
for e in sys.stdin:e=int(e);print(e*(e+1)//2+1)

Python: # -*- coding: utf-8 -*-

import sys
import os

for s in sys.stdin:
    n = int(s)
    if n == 1:
        print(2)
    else:
        num = 2
        for i in range(2, n+1):
            num += i
        print(num)

Python: d= dict()
j=v= 2

for i in range(1, 10001):
    d[i]= v
    if i%2==0: j+= 1
    v+= j

while True:
    try:
        l= int(input())
    except:
        break
    print(d[l])

Python: def get_input():
    while True:
        try:
            yield ''.join(input())
        except EOFError:
            break

N = list(get_input())
for l in range(len(N)):
    n = int(N[l])
    print(n*(n+1)//2+1)

Python: # -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0057
"""
import sys


Area_memo = [0 for _ in range(10002)]         #  n??¬???????????????????????????????????° (0???????¨????)
Area_memo[0] = 1
def count_area(num):
    """
    ????????°??¨???????????°?????¢????????\????????????????????£????????????
    0 -> 1
    1 -> 2
    2 -> 4
    3 -> 7
    4 -> 11
    ?????£??????i??¬???????????????????????????????????°??????(i-1)??¬????????????????????° + ????????° ??¨?????????
    n?????°????????§??§10,000????????§????????¢???????????????????????????
    :param num:????????°
    :return: ???????????°
    """
    global Area_memo
    if Area_memo[num] == 0:
        Area_memo[num] = num + count_area(num-1)
    return Area_memo[num]


def main(args):
    for line in sys.stdin:
        num = int(line.strip())
        result = count_area(num)
        print(result)


if __name__ == '__main__':
    main(sys.argv[1:])

Python: import sys
readlines = sys.stdin.readlines
write = sys.stdout.write
def solve():
    for line in readlines():
        N = int(line)
        write("%d\n" % (N*(N+1)//2+1))
solve()

Python: an = [1]
for i in range(1, 10001):
    an.append(an[i-1] + i)

while True:
    try:
        n = int(input())
    except:
        break
    print(an[n])

Python: # -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0057
"""
import sys


Area_memo = [0 for _ in range(10002)]         #  n??¬???????????????????????????????????° (0???????¨????)
Area_memo[0] = 1
def count_area(num):
    """
    ????????°??¨???????????°?????¢????????\????????????????????£????????????
    0 -> 1
    1 -> 2
    2 -> 4
    3 -> 7
    4 -> 11
    ?????£??????i??¬???????????????????????????????????°??????(i-1)??¬????????????????????° + ????????° ??¨?????????
    n?????°????????§??§10,000????????§????????¢???????????????????????????
    ??? ?????????????????¨???n?????§????????¨?????°????????????????????°????¢???????????????¨???????????????
    :param num:????????°
    :return: ???????????°
    """
    global Area_memo
    if Area_memo[num] == 0:
        Area_memo[num] = num + count_area(num-1)
    return Area_memo[num]


def count_area2(num):
    wa = num * (1 + num) // 2
    return wa + 1



def main(args):
    for line in sys.stdin:
        num = int(line.strip())
        result = count_area2(num)
        print(result)


if __name__ == '__main__':
    main(sys.argv[1:])

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

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

C++: #include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
#include<functional>
using namespace std;
int stoi(string x){stringstream ss;ss<<x;int tmp;ss>>tmp;return tmp;}
string itos(long double x){stringstream ss;ss<<x;return ss.str();}
int main(){
int n,ans=1;
while(cin>>n){
ans=1;
for(int i=0;i<n;i++)ans+=(i+1);
cout<<ans<<endl;
}
return 0;
}