Problem:
 Score : 100 points    Problem Statement There are N children in AtCoder Kindergarten. Mr. Evi will arrange the children in a line, then give 1 candy to the first child in the line, 2 candies to the second child, ..., N candies to the N -th child. How many candies will be necessary in total?      Constraints  1≦N≦100         Input The input is given from Standard Input in the following format:  N       Output Print the necessary number of candies in total.        Sample Input 1 3      Sample Output 1 6  The answer is 1+2+3=6 .       Sample Input 2 10      Sample Output 2 55  The sum of the integers from 1 to 10 is 55 .       Sample Input 3 1      Sample Output 3 1  Only one child. The answer is 1 in this case.

Solution (Python):
n = int(input())
candy = 0
for x in range(0, n+1):
  candy += x
print(candy)

Solution (Python):
n = int(input())
print(n * (1 + n) // 2)

Solution (Python):
n = int(input())

ans = 0
for i in range(1, n + 1):
    ans += i

print(ans)

Solution (Python):
n = int(input())
print(int((n+1)*n*(1/2)))

Solution (Python):
N = int(input())
ans = 0;
for i in range(1, N+1):
    ans += i
print(ans)

Solution (Python):
n = int(input())
print(int((1+n)*n*(1/2)))

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
N =int(input())
candy = 0
for i in range(N+1):
    candy += i
print(candy)

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
N = int(input())

print( N * (N + 1) // 2)

Solution (Python):
n = int(input())
if n == 1:
    print(n)
else:
    print(int((1+n)*n/2))

Solution (Python):
n=int(input())
ans=0
for i in range(1,n+1):
    ans+=i
print(ans)

Solution (Python):
a = int(input())
print(int(0.5*a*(a+1)))

Solution (Python):
N = int(input())
candy = 0
for i in range(1, N+1):
    candy += i
print(candy)

Solution (Python):
n=int(input())
print(int(n*(n+1)/2))

Solution (Python):
n = int(input())
sum = 0
for i in range(1, n + 1):
    sum = sum + i
print(sum)

Solution (Python):
n = int(input())
s = sum([i for i in range(1,n+1)])
print(s)

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
n=int(input())
d=n*(n+1)/2
print(int(d))

Solution (Python):
N = int(input())
S = 0
for i in range(1, N+1):
  S += i
print(S)

Solution (Python):
n= int(input())
print(int((1+n)*n/2))

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
n = int(input())
print(int(n*(1+n)/2))

Solution (Python):
N = int(input())
print(int(1/2*N*(N+1)))

Solution (Python):
n = int(input())
s = 0
for i in range(n):
  s += i + 1
print(s)

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
nl = lambda: list(map(int, input().split()))
sl = lambda: input().split()
n = lambda: int(input())
s = lambda: input()

N = n()
print((N + 1) * N // 2)

Solution (Python):
n = int(input())
print(int(n*(n+1)/2))

Solution (Python):
n=int(input())
print((n*(n+1))//2)

Solution (Python):

import copy
import random
import bisect 
import fractions 
import math
import sys

mod = 10**9+7
sys.setrecursionlimit(mod) 

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())

N = int(input())
print(N*(N+1)//2)

Solution (Python):
n = int(input())
print((n + 1) * n // 2)

Solution (Python):
N = int(input())

ans = 0
for i in range(1, N + 1):
    ans += i
print(ans)

Solution (Python):
n = int(input())
s = 0
for i in range(n):
  s += i + 1
print(s)

Solution (Python):
n = int(input())
s = 0
for i in range(n):
  s += i + 1
print(s)

Solution (Python):
n=int(input());print(n*(n+1)//2)

Solution (Python):
N=int(input())
print(int((1+N)*N/2))

Solution (Python):
x = int(input())

print(x*(x + 1)//2)

Solution (Python):
all = int(input())
a = 0
for i in range(1, all + 1):
    a += i
print(a)

Solution (Python):
N = int(input())
print(N * (N+1) // 2)

Solution (Python):
N = int(input())
print(N * (N + 1) // 2)

Solution (Python):
import sys
input = sys.stdin.readline

n = int(input())
sum = 0
for i in range(1, n+1):
    sum += i
print(sum)

Solution (Python):
n=int(input())
print(int((1+n)*n/2))

Solution (Python):
n = int(input())
result = 0
for i in range(1, n+1):
    result += i

print(result)

Solution (Python):
n = int(input())
print(n * (n + 1) // 2)

Solution (Python):
N = int(input())
ans = 0
for i in range(1,N+1):
    ans += i
print(ans)

Solution (Python):
N = int(input())
can =0
for i in range(1,N+1):
  can+=i
  
  
print(can)

Solution (Python):
n = int(input())

ans = 0
for i in range(1, n + 1):
  ans += i
  
print(ans)

Solution (Python):
n = int(input())
ans = 0
for i in range(n):
  ans += (i+1)
print(ans)

Solution (Python):
n=int(input())
print(int((1+n)*n/2))

Solution (Python):
def main():
    n = int(input())
    ans = (1+n)*n/2
    print(int(ans))
if __name__=='__main__':
    main()

Solution (Python):
def abc():
    x = int(input())
    print(sum(range(1, x + 1)))


abc()

Solution (Python):
Sum = 0
x=int(input())+1
for i in range(x):
    Sum = Sum + i
print(Sum)

Solution (Python):
n = int(input())

c = 0
for i in range(n+1):
    c +=i
print(c)

Solution (Python):


n = int(input())

ans = 0
for i in range(1, n+1):
    ans += i
print(ans)

Solution (Python):
n = int(input())
sum = 0
i = 1
for i in range(n + 1):
    sum = sum + i
    
    
print(sum)

Solution (Python):
n = input()
a = 0
b = 0
for i in range(n):
    b = b + 1
    a = a + b
print a

Solution (Python):
n = int(input())

sum = 0
for i in range(1, n+1):
    sum += i
print(sum)

Solution (Python):
N = int(input())
print(int(((1+N)/2)*N))

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
N=int(input())
i=0
for k in range(1,N+1):
    i=i+k
print(i)

Solution (Python):
n=int(input())
print((n+1)*n//2)

Solution (Python):
childrenNum = int(input())
candySum = 0

for i in range(1, childrenNum + 1):
    candySum += i

print(candySum)

Solution (Python):
n = int(input())
ans = 0
for i in range(n):
  ans += i+1
print(ans)

Solution (Python):
N = input()
sum = 0
for i in range(1,int(N) + 1):
  sum = sum + i
  
print(sum)

Solution (Python):
n = int(input())
print(n * (n + 1) // 2)

Solution (Python):
a = int(input())
ans = 0
for x in range(a+1):
    ans += x
print(ans)

Solution (Python):
a=int(input())
print((1+a)*a//2)

Solution (Python):
N = int(input())
print(int((1+N)*N/2))

Solution (Python):
n=int(input())

print(int((1+n)*n/2))

Solution (Python):
a=int(input())

print(a*(a+1)//2)

Solution (Python):
child = int(input())

candy = 0

for i in range(child):
    candy += i+1

print(candy)

Solution (Python):
n = int(input())
print((n*(n+1))//2)

Solution (Python):
a=int(input())
s=a*(a+1)/2
print(int(s))

Solution (Python):
N = int(input())
print(N * (N + 1) // 2)

Solution (Python):
i=int(input())
print((i*(i+1))//2)

Solution (Python):
N = int(input())
answer = 0
for i in range(N+1):
    answer += i
print(answer)

Solution (Python):
N = int(input())
answer = 0
for i in range(N+1):
  answer += i
print(answer)

Solution (Python):

import sys
def input(): return sys.stdin.readline().rstrip()
def mi(): return map(int, input().split())


N = int(input())

cnt = 0
for i in range(1, N+1):
  cnt += i

print(cnt)

Solution (Python):
n = int(input())
print( int(n*(n+1)/2))

Solution (Python):
n = int(input())

print(n * (n+1) // 2)

Solution (Python):
a = int(input())

result = 0
for i in range(a):
    

    
    result = result + (i + 1)

print(result)

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
N = int(input())
print(N * (N + 1) // 2)

Solution (Python):
a = input()
print(a * (a + 1)/2)

Solution (Python):
a=int(input())
ans=0
for i in range(a+1):
  ans+=i
print(ans)

Solution (Python):
n=int(input())
print((1+n)*n//2)

Solution (Python):
n = int(input())
ans = 0
for i in range(1,n+1):
    ans+=i
print(ans)

Solution (Python):
n=int(input())
i=0
for m in range(n+1):
	i=i+m
print(i)

Solution (Python):
N=int(input())
print(N*(N+1)//2)

Solution (Python):
N = int(input())
ans = 0
for i in range(N):
  ans += i+1
print(ans)

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
N = int(input())
print(int((N+1)/2*N))

Solution (Python):
n = int(input())
print(n * (n + 1) // 2)

Solution (Python):
n = int(input())
print(int(n * (n + 1) / 2))

Solution (Python):
n=int(input())
c=0
for i in range(1,n+1):
    c+=i
print(c)

Solution (Python):
n=int(input())
c=0
for i in range(1,n+1):
    c+=i
print(c)

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
n=int(input())
print(int((1+n)*n/2))

Solution (Python):
N = int(input())

ans = N*(N+1) // 2

print(ans)

Solution (Python):
print(sum(range(1, int(input())+1)))

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
n = int(input())
m = 0
for i in range(n):
  m += i+1
print (m)

Solution (Python):
a = int(input())
y = 0
for x in range(a+1):
        y += x
print(y)

Solution (Python):
n = int(input())
l = list(range(1, n+1))

print(sum(l))

Solution (Python):
i = int(input())
sum = 0
for i in range(i+1):
    sum += i
print(sum)

Solution (Python):
n=int(input())
s=0
for i in range(1,n+1):
	s+=i
print(s)

Solution (Python):
n = int(input())
result = 0
for i in range(1,n+1):
    result += i
print(result)

Solution (Python):
n = int(input())
result = 0
for i in range(1,n+1):
    result += i
print(result)

Solution (Python):
n=int(input())

allnum = 0

for i in range(n+1):
  allnum += i
  
print(allnum)

Solution (Python):
n = int(input())
print((n*(n+1))//2)

Solution (Python):
n = int(input())
if n!=1:
  print(int(n*(n+1)/2))
else:
  print(1)

Solution (Python):
n = int(input())
print(int(n * (n+1)/2))

Solution (Python):
a=int(input())
answer=0
for i in range(1,a+1):
  answer+=i
print(answer)

Solution (Python):
N=int(input())
print(N*(N+1)//2)

Solution (Python):
n = int(input())

Answer = n*(n+1)/2

print(int(Answer))

Solution (Python):
n=int(input())

sum=0
for i in range(n+1):
	sum += i;

print(sum)

Solution (Python):
N = int(input())

print(((1+N)*N)//2)

Solution (Python):
N = int(input())
candy = 0
for i in range(N+1):
    candy += i
print(candy)

Solution (Python):
n=int(input())

answer=[]

for i in range(1,n+1):
    answer.append(i)

print(sum(answer))

Solution (Python):

 

n = int(input())


sum = 0

for num in range(n+1) :
    sum += num
    

print(sum)

Solution (Python):
print(sum(range(1, int(input())+1)))

Solution (Python):
a = int(input())
print(a*(a+1)//2)

Solution (Python):
n = int(input())
sum = 0
for i in range(n):
  sum += i+1
print(sum)

Solution (Python):
N = int(input())

print(int((1 + N) * N / 2))

Solution (Python):
N = int(input())
g = 0
for n in range(1, N+1):
    g += n
print(g)

Solution (Python):
N = int(input())
print(int(N*(N+1)/2))

Solution (Python):
N = int(input())
ans = 0
for i in range(N):
    ans += i + 1
print(ans)

Solution (Python):
N = int(input())
ans = 0
for i in range(N):
    ans += i + 1

print(ans)

Solution (Python):
n = int(input())
sum = 0
for x in range(n):
  	sum = sum + x +1
print(sum)

Solution (Python):
N = int(input())
result = N * (N + 1) // 2
print(result)

Solution (Python):
a=int(input())
b=0
for i in range(a):
    b=a+b
    a -=1
print(b)

Solution (Python):
n = int(input()) 
print(n*(n+1)//2)

Solution (Python):
n = int(input())
value = 0
for i in range(1,n+1):
    value += i
print(value)

Solution (Python):
N = int(input())
required_candy = 0
for i in range(1,N+1):
    required_candy += i

print(required_candy)

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
N = int(input())
print(int((1 + N) * (N / 2)))

Solution (Python):
n = int(input())
print(int((1+n)/2*n))

Solution (Python):
N=int(input())
print(N*(N+1)//2)

Solution (Python):
N = int(input()) 

print((1+N)*N//2)

Solution (Python):
N=int(input());print(N*(N+1)//2)

Solution (Python):
N = int(input())
S = int(N*N/2+N/2)
print(S)

Solution (Python):
N = int(input())
print(sum(range(1, N+1)))

Solution (Python):
N=int(input())

print(int((N+1)*N/2))

Solution (Python):
N = int(input())
print(sum(i for i in range(1,N+1)))

Solution (Python):
n = int(input())
ans = 0
for i in range(1,n+1):
  ans += i
print(ans)

Solution (Python):
N = int(input())
cnt = 0
for i in range(N+1):
    cnt += i
print(cnt)

Solution (Python):
n = int(input())
a = list(range(1,n+1))
b = sum(a)
print(b)

Solution (Python):


n = int(input())

a = 0
for i in range(1, n+1):
    a += i
    
print(a)

Solution (Python):
n = int(input())

ans = 0
for i in range(1, n + 1):
    ans += i
print(ans)

Solution (Python):
def main():
	N = int(input())
	print(((N+1)*N)//2)


if __name__ == '__main__':
	main()

Solution (Python):
N = int(input())
ans = 0
for i in range(N):
    ans += i + 1
print(ans)

Solution (Python):
n=int(input())
print(int(1/2*n*(n+1)))

Solution (Python):
N = int(input())
print(int(N * (N + 1) / 2))

Solution (Python):
n = int(input())
print(sum(list(range(n+1))))

Solution (Python):
print(sum(range(int(input())+1)))

Solution (Python):
n = int(input())
print(int(0.5*n*(n+1)))

Solution (Python):
Person = int(input())

Candy = 0

for i in range(Person):

    Candy += i+1

print(Candy)

Solution (Python):
n=int(input())
     
print(int(n*(n+1)/2))

Solution (Python):
a = int(input())
print(int(a*(a+1)/2))

Solution (Python):
n = int(input())
ans = 0

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

Solution (Python):
N = int(input())
print(N * (N+1) // 2)

Solution (Python):
n = int(input())
cnt=0

for i in range(1,n+1):
    cnt+=i
print(cnt)

Solution (Python):
N=int(input())
print(N*(N+1)//2)

Solution (Python):
n=int(input())
ans=0
for i in range(n+1):
    ans+=i
print(ans)

Solution (Python):
n = int(input())
print(int(1/2*n*(n+1)))

Solution (Python):
n=int(input())
     
sum=n*(n+1)/2
     
print(int(sum))

Solution (Python):
print(sum(range(int(input())+1)))

Solution (Python):
from collections import Counter, deque
from fractions import gcd
from functools import lru_cache
from functools import reduce
import functools
import heapq
import itertools
import math
import numpy as np
import sys

sys.setrecursionlimit(10000)
INF = float('inf')

N=int(input())


a = 1
ans = 0
for i in range(N):
    ans += a
    a += 1

print(ans)

Solution (Python):
def main():
    N = int(input())
    print(int((1 + N) * N / 2))
if __name__ == "__main__":
    main()

Solution (Python):
a = int(input())
print(int((1+a)*a/2))

Solution (Python):
L = int(input())
print(int(L*(L+1)/2))

Solution (Python):
N = int(input())

ans = N*(N+1)//2

print(ans)

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):

def read_input():
    n = int(input())
    return n


def submit():
    n = read_input()
    print(int(n * (n + 1) / 2))


if __name__ == '__main__':
    submit()

Solution (Python):
N = int(input())
s = 0
for i in range(N):
  s += i + 1
print(s)

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
N = int(input())
print(sum(list(range(1, N+1))))

Solution (Python):
n=int(input())
ans = 0
for i in range(n+1):
  ans += i
print(ans)

Solution (Python):
a=int(input())
print(a*(a+1)//2)

Solution (Python):


print(sum([i for i in range(1, int(input()) + 1)]))

Solution (Python):
N=int(input());print(N*(N+1)//2)

Solution (Python):
n = int(input())
print(n * (n + 1) // 2)

Solution (Python):
print(sum(range(1, int(input())+1)))

Solution (Python):
a=input()
a=int(a)
b=(a*(a+1))//2
print(b)

Solution (Python):
a=int(input())
print(a*(a+1)//2)

Solution (Python):
n = int(input())
l = [i + 1 for i in range(n)]

print(sum(l))

Solution (Python):

import numpy as np

def solve(N):
    sum = 0
    for i in range(1, N+1):
        sum += i
    print(sum)
    
if __name__ == '__main__':
    N = int(input())
    
    solve(N)

Solution (Python):
n=int(input())
sum=0

if n%2==0:
    flag=int(n/2)
    for i in range(flag):
        sum=sum+(n+1)
else:
    flag=int((n-1)/2)
    for i in range(flag):
        sum=sum+(n+1)
    sum=sum+((n+1)/2)

print(int(sum))

Solution (Python):
import sys

def main():
    input = sys.stdin.readline
    N = int(input())
    return N*(N+1)//2

if __name__ == '__main__':
    print(main())

Solution (Python):


N = int(input())

number = 0
for i in range(1, N + 1):
    number += i
print(number)

Solution (Python):

n = int(input())
total = 0
for i in range(1, n + 1):
    total += i
print(total)

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
n = int(input())

total = (n + 1)*n//2
print(total)

Solution (Python):
N = int(input())

print((N*(N+1))//2)

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
n=int(input())

print(n*(n+1)//2)

Solution (Python):
num = int(input())
cnt = 0
for i in range(num):
  cnt += i + 1
print(cnt)

Solution (Python):
n = int(input())
sum = 0

for i in range(1, n + 1):
    sum += i

print(sum)

Solution (Python):
N=int(input())
print(N*(N+1)//2)

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
n = int(input())
cnt = 0
for i in range(1,n+1):
    cnt += i
print(cnt)

Solution (Python):
n = int(input())
isum = 0
for i in range(n+1):
    isum += i
print(isum)

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
n= int(input())
print(int(n*(n+1)/2))

Solution (Python):
n = int(input())
print(int(n*(n+1)/2))

Solution (Python):
n = int(input())

print(int(n*(n+1)/2))

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
N = int(input())
ans = 0
for i in range(N):
  ans += N
  N -= 1
print(ans)

Solution (Python):
from sys import stdin
input=stdin.readline().rstrip()
input=int(input)
sum=0
for i in range(input+1):
  sum+=i
  
print(sum)

Solution (Python):
n = int(input())
print(int(n * (n + 1) / 2))

Solution (Python):
n = int(input())
res = 0
for i in range(n+1):
  res += i
print(res)

Solution (Python):
a = int(input())
sum = 0
for i in range(a+1):
  sum += i
print(sum)

Solution (Python):
n=int(input())
sum=0
for i in range(n+1):
  sum+=i
print(sum)

Solution (Python):
N =int(input())
print(int(N*(N+1)/2))

Solution (Python):
n=input()
n=int(n)
a=0
for i in range(1,n+1):
    a=a+i
print(a)

Solution (Python):


n = int(input())

sum = 0

for i in range(1, n+1):
    sum += i
print(sum)

Solution (Python):
x = int(input())
print(int((x**2 + x) /2))

Solution (Python):
from sys import stdin

n = int(stdin.readline().rstrip())
total = 0
for i in range(1, n+1):
    total += i
print(total)

Solution (Python):
x = int(input())
print(int(x*(x+1)/2))

Solution (Python):
N = int(input())
a = int(N * ( N + 1 ) / 2)
print(a)

Solution (Python):
n = int(input())

print(n*(1+n)//2)

Solution (Python):
print(sum([n for n in range(1, int(input())+1)]))

Solution (Python):
n = int(input())

c = 0
for i in range(n):
    c += i +1

print(c)

Solution (Python):
n=int(input());print(n*-~n//2)

Solution (Python):
N = int(input())
print(int((1+N)*N/2))

Solution (Python):
def children_and_candies(N: int)->int:
    return N * (N + 1) // 2


if __name__ == "__main__":
    N = int(input())
    ans = children_and_candies(N)
    print(ans)

Solution (Python):
a = int(input())
b = range(a+1)
print(sum(b))

Solution (Python):
n = input()
ya  = 0
for i in range(1,int(n) + 1):
		
	ya += i
print(ya)

Solution (Python):
n = int(input())
cnt = 0
 
for i in range(n + 1) :
  cnt += i
print(cnt)

Solution (Python):
N = int(input())
result = 0
for i in range(N+1):
  result += i
print(result)

Solution (Python):
N = int(input())
cnt = 0
for i in range(N+1):
    cnt += i
print(cnt)

Solution (Python):
from sys import stdin

N = int(stdin.readline().rstrip())
result = 0

for i in range(1, N+1):
    result += i
print(result)

Solution (Python):
N = int(input())

cnt = 0
for i in range(N+1):
    cnt += i
print(cnt)

Solution (Python):
N = int(input())

ans = 0
for i in range(N):
    ans += i+1

print(ans)

Solution (Python):
N=int(input())
print(int(N*(N+1)/2))

Solution (Python):
N = int(input())
print(N*(1+N)//2)

Solution (Python):
n = int(input())
print(n * (n + 1) // 2)

Solution (Python):
n = int(input())
a = 0
for i in range(1, n+1):
    a += i
print(a)

Solution (Python):
N = int(input())
count = 0
 
 
for i in range(N+1):
    count += i 
    
print(count)

Solution (Python):


n = int(input())
x = 0
for z in range(0,n+1):
    x += z
print(x)

Solution (Python):
N = int(input())
count = 0
for i in range(N):
    count += i + 1
print(count)

Solution (Python):
n = int(input())

print(int(n*(n+1)/2))

Solution (Python):
N=int(input())
ans=(N*(N+1))//2
print(ans)

Solution (Python):
from sys import stdin
input = stdin.readline
N = int(input())
print(int(1/2 * N * (N+1)))

Solution (Python):
def main():
    N = int(input())
    total = 0
    for i in range(N+1):
        total += i
    print(total)
main()

Solution (Python):
n=int(input())

ans=(1+n)*n//2
print(ans)

Solution (Python):
N = int(input())
a = N*(N+1)/2
print(int(a))

Solution (Python):
n = int(input())
print(  n * (n+1) // 2 )

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
N = int(input())
print(int(0.5*N*(N+1)))

Solution (Python):

from collections import defaultdict
from heapq import heappush, heappop
import sys
import math
import bisect
import random
def LI(): return list(map(int, sys.stdin.readline().split()))
def I(): return int(sys.stdin.readline())
def LS():return list(map(list, sys.stdin.readline().split()))
def S(): return list(sys.stdin.readline())[:-1]
def IR(n):
    l = [None for i in range(n)]
    for i in range(n):l[i] = I()
    return l
def LIR(n):
    l = [None for i in range(n)]
    for i in range(n):l[i] = LI()
    return l
def SR(n):
    l = [None for i in range(n)]
    for i in range(n):l[i] = S()
    return l
def LSR(n):
    l = [None for i in range(n)]
    for i in range(n):l[i] = SR()
    return l
mod = 1000000007


n = I()
print((n*(n+1))//2)





"""
s = S()
l = len(s)
for i in range(l-1):
    if s[i] == s[i+1]:
        print(i+1,i+2)
        quit()
for i in range(l-2):
    if s[i] == s[i+2]:
        print(i+1,i+3)
        quit()
print(-1,-1)
"""

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
from functools import reduce

def main():
    
    
    
    
    

    
    
    n = int(input().rstrip())
    ans = 0
    for i in range(1,n+1):
        ans = ans + i
    print(ans)    
   
if __name__ == '__main__':
    main()

Solution (Python):

def main():
  a = int(input())
  print(int(((a+1)*a)/2))

if __name__=='__main__':main()

Solution (Python):
N=int(input())
ans=0
for i in range(N):
  ans+=i+1
print(ans)

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
N = int(input())

count = 0

for i in range(N):
	count += i+1

print(count)

Solution (Python):
print(sum(range(int(input())+1)))

Solution (Python):
n=int(input())
z=0
for i in range(1,n+1):
    z+=i
print(z)

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
N  = int(input())
print((1+N)*(N)//2)

Solution (Python):
N  = int(input())
ans = 0
for i in range(N+1):
  ans += i
print(ans)

Solution (Python):
n = int(input())

res = 0
for i in range(n+1):
    res+=i
print(res)

Solution (Python):
N = int(input())
print(N*(N+1)//2)

Solution (Python):
N = int(input())

ans = 0
for i in range(N):
	ans += i+1

print(ans)

Solution (Python):
n=int(input())
def calc(n):
    if n==1:
        return 1
    else:
        return n+calc(n-1)
print(calc(n))

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
def main():
    N = int(input())
    print((1+N)*N//2)


if __name__ == "__main__":
    main()

Solution (Python):
import numpy as np

N = int(input())
all_list = [i for i in range(1, N+1)]
result = np.cumsum(all_list)
print(max(result))

Solution (Python):
N = int(input())

answer = 0

for i in range(1, N+1):
    answer += i

print(answer)

Solution (Python):
N = int(input())
print(sum([i for i in range(N+1)]))

Solution (Python):
n = int(input())
print(int((n+1)*(n/2)))

Solution (Python):
print(sum([x for x in range(1,int(input())+1)]))

Solution (Python):

n = int(input())
children = list(i for i in range(1, n+1))
answer = sum(children)
print(answer)

Solution (Python):
print(sum([_ for _ in range(1,int(input())+1)]))

Solution (Python):
N = int(input())
print(sum([i for i in range(1,N+1)]))

Solution (Python):

N = int(input())

ans = 0
for i in range(1, N + 1):
    ans += i
print(ans)

Solution (Python):

n = int(input())
print(int(n*(n+1)/2))

Solution (Python):


N = int(input())

print(int(N*(N+1)/2))

Solution (Python):
N = int(input())
n_sum = int((1+N)*N/2)
print(n_sum)

Solution (Python):
input_str = int(input())
result = 0




for i in range(1, input_str+1):
    result += i
print(result)

Solution (Python):
input_str = int(input())
result = 0
for i in range(1, input_str+1):
    result += i
print(result)

Solution (Python):
N = int(input())
print(sum([i for i in range(1, N+1)]))

Solution (Python):
n=int(input());print(n*(n+1)//2)

Solution (Python):
n=int(input());print(round(n*(n+1)/2))

Solution (Python):
N=int(input())
print(int(N*(N+1)/2))

Solution (Python):
N=int(input())
print(str(int(N*(N+1)/2)))

Solution (Python):
n = int(input())

ans = 0
for i in range(n):
    ans += i + 1

print(ans)

Solution (Python):
def main() -> None:
    N = int(input())
    s = 0
    for i in range(N + 1):
        s += i
    print(s)


if __name__ == '__main__':
    main()

Solution (Python):
n = int(input())

a = []
a = [i for i in range(1, n+1)]
print(sum(a))

Solution (Python):
n=int(input())
print(int(n*(n+1)/2))

Solution (Python):
from itertools import combinations, product


def gcd(a, b):
    if a < b:
        a, b = b, a
    while b != 0:
        a, b = b, a % b
    return a

def lcm(a, b):
    return a * b // gcd(a, b)


def get(fmt):
    ps = input().split()
    r = []
    for p, t in zip(ps, fmt):
        if t == "i":
            r.append(int(p))
        if t == "f":
            r.append(float(p))
        if t == "s":
            r.append(p)
    if len(r) == 1:
        r = r[0]
    return r

def put(*args, **kwargs):
    print(*args, **kwargs)


def rep(n, f, *args, **kwargs):
    return [f(*args, **kwargs) for _ in range(n)]
    
def rep_im(n, v):
    return rep(n, lambda: v)
    
YES_NO = ["NO", "YES"]


N = get("i")

put(N * (N + 1) // 2)

Solution (Python):
N=int(input())
print(N*(N+1)//2)

Solution (Python):
n = input()
sum_candy = 0
for i in range(int(n)):
    sum_candy = sum_candy + i +1
print(sum_candy)

Solution (Python):
n = int(input())
print((n + 1) * n // 2)

Solution (Python):
n = [i+1 for i in range(int(input()))]
print(sum(n))

Solution (Python):
n = int(input())
ans = 0
for i in range(1, n+1):
    ans += i
print(ans)

Solution (Python):
n = int(input())

print(n*(n+1)//2)

Solution (Python):
N = int(input())
print(round(N*(N+1)/2))

Solution (Python):
print(sum([i+1 for i in range(int(input()))]))

Solution (Python):
def main():
  N = int(input())
  sum = 0
  for i in range(1,N+1):
    sum = sum + i
  print(sum)

main()

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):

n = int(input())
print((n + 1) * n // 2)

Solution (Python):
n=int(input());print(n*-~n//2)

Solution (Python):
n=int(input());print(n*(n+1)//2)

Solution (Python):
print(sum(range(int(input())+1)))

Solution (Python):
N = int(input())
ans = 0

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

Solution (Python):
n = int(input())
a = 0

for i in range(1, n+1):
        a = a + i

print(a)

Solution (Python):
n = int(input())
k = 0
for i in range(n+1):
  k += i
print(k)

Solution (Python):
N = int(input())
sum = 0
for i in range(N+1):
	sum += i

print(sum)

Solution (Python):
N = int(input())
ans = N*(N+1)//2
print(ans)

Solution (Python):
N = int(input())
print((N*(N+1))//2)

Solution (Python):
a=int(input())
print(int(a*(a+1)/2))

Solution (Python):
n=int(input())
ans=int(n*(n+1)/2)
print(ans)

Solution (Python):
N = int(input().rstrip())

v = (1 + N) * int(N / 2)
if N % 2 == 1:
    v += int(N / 2) + 1

print(v)

Solution (Python):
a =int(input())
b=0
for i in range(1,a+1):
  b=b+i
print(b)

Solution (Python):
A=int(input())
N=0
for i in range(1,A+1):
  N+=i
print(N)

Solution (Python):
N = int(input())
print((N+1)*N // 2)

Solution (Python):
from sys import stdin
a = int(stdin.readline().rstrip())
print(sum([i for i in range(1, a+1)]))

Solution (Python):
n = int(input())
a = [i for i in range(n+1)]

print(sum(a))

Solution (Python):
n = int(input())
total = 0
for i in range(n+1):
    total += i
print(total)

Solution (Python):
N = int(input())
result = N * (1 + N) // 2
print(result)

Solution (Python):
ans = 0
for i in range(1,int(input())+1):
    ans += i
print(ans)

Solution (Python):
n = int(input())
print(n * (n+1) // 2)

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
N = int(input())

if N%2==0:
  print(int((N+1)*N/2))
else:
  print(int((N+1)*(N//2)+(N-N//2)))

Solution (Python):
n = int(input())
print(int(n*(n+1)/2))

Solution (Python):
N = int(input())
ans = 0
for i in range(1, N+1):
    ans += i
print(ans)

Solution (Python):
n=int(input())
ans=0
for i in range(n+1):
    ans+=i
print(ans)

Solution (Python):
n = int(input())
print(sum([i for i in range(1, n+1)]))

Solution (Python):
n = int(input())

sum = 0
for i in range(1,n+1):
    sum += i

print (sum)

Solution (Python):
n = int(input())
print(sum([i for i in range(1,n+1)]))

Solution (Python):

n = int(input())
print(n * (n + 1) // 2)

Solution (Python):
N = int(input())
sum = int(N*(N+1)/2)
print(sum)

Solution (Python):
a=int(input())
sum=0
for i in range(a+1):
 sum=sum+i

print(sum)

Solution (Python):
Sum=0
N=int(input())
for i in range(N):
  Sum+=i+1
print(Sum)

Solution (Python):
N = int(input())
count = 0
for i in range(1,N+1):
  count += i

print(count)

Solution (Python):
N = int(input())
print(int(N*(N+1)/2))

Solution (Python):

N = int(input())
ans = 0
for i in range(N+1):
    ans +=i
print(ans)

Solution (Python):

N = int(input())
ans = 0
for i in range(N+1):
    ans +=i
print(ans)

Solution (Python):
n=int(input())
ans=0
for i in range(n+1):
    ans+=i
print(ans)

Solution (Python):
N=int(input())
total=0
for i in range(N):
  total += i+1
print(total)

Solution (Python):
a = input()
b = 0
for x in range(int(a)+1):
    b+=x
print(b)

Solution (Python):
n=int(input())
print(n*(n+1)//2)

Solution (Python):
N = int(input())

def dfs(n):
  ret = 0
  for i in range(1,n+1):
    ret += i
  return ret
print(dfs(N))

Solution (Python):
a = int(input())
sum = 0
for i in range(a):
  sum += i+1
print(sum)

Solution (Python):
N = int(input())
ans = 0
for i in range(1,N+1):
  ans += i
print(ans)

Solution (Python):
N = int(input())
print((1 + N) * N // 2)

Solution (Python):
a = int(input())
print(int(a*(a+1)/2))

Solution (Python):
a=int(input())
sum=0
while a>0:
  sum=sum+a
  a=a-1

print(sum)

Solution (Python):
n = int(input())
print( (n * (n+1)) // 2)

Solution (Python):
N=int(input())
sum=0
for i in range(N+1):
    sum=sum+i
print(sum)

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
n = int(input())
print(int((1/2)*n*(n+1)))

Solution (Python):
n = int(input())
result = 0
for i in range(1,n+1):
    result += i

print(result)

Solution (Python):
n = int(input())
print(int(n*(n+1)/2))

Solution (Python):
N=input()
print N*(N+1)/2

Solution (Python):
n = int(input())
print(n*(n+1)//2)

Solution (Python):
s=int(input())
print(int(s*(s+1)/2))

Solution (Python):
N = int(input())

from operator import add
from functools import reduce
ans = reduce(add, range(N)) + N

print(ans)
print()