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):
import sys
stdin = sys.stdin
inf = 1 << 60
mod = 1000000007
 
ni      = lambda: int(ns())
nin     = lambda y: [ni() for _ in range(y)]
na      = lambda: list(map(int, stdin.readline().split()))
nan     = lambda y: [na() for _ in range(y)]
nf      = lambda: float(ns())
nfn     = lambda y: [nf() for _ in range(y)]
nfa     = lambda: list(map(float, stdin.readline().split()))
nfan    = lambda y: [nfa() for _ in range(y)]
ns      = lambda: stdin.readline().rstrip()
nsn     = lambda y: [ns() for _ in range(y)]
ncl     = lambda y: [list(ns()) for _ in range(y)]
nas     = lambda: stdin.readline().split()

n = ni()
print(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+=i+1
print(ans)

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

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

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

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

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

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

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

a = 0 

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

print(a)

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

Solution (Python):
def resolve(n):
    def ans(n, a):
        if n == 0:
            return a
        else:
            a += n
            return ans(n-1,a)
    return ans(n, 0)

print(resolve(int(input())))

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

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

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

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

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

Solution (Python):
a = input()
a = int(a) +1
add = 0

for i in range(a):
    add = add + i

print(add)

Solution (Python):
def candy(N):
    return (N**2 +N)//2

N = int(input())
print(candy(N))

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

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

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

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

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

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

resolve()

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

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

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

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

Solution (Python):
N = input()
N = int(N)
x = N
total = 0
while x >=1:
    total += x
    x = x - 1
else: print(total)

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

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

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

Solution (Python):
icase=43
        
if icase==43:
    n=int(input())
    print(n*(n+1)//2)

Solution (Python):
N = int(input())
sum = 0
for i in range(N+1):
    sum += i
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(int(n * (n+1) / 2))

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

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

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

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

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

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

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

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

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

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

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

sum = 0

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

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

total=0

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

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

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

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

Solution (Python):

N = int(input())

ans = sum([i + 1 for i in range(N)])
print(ans)

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

if n % 2 == 0:
  ans = (n+1) * n/2
else:
  ans = (n+1) * (n // 2) + (n // 2 + 1)

print(int(ans))

Solution (Python):
import sys

input = sys.stdin.readline


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


if __name__ == "__main__":
    main()

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

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

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


nancy = int(input())

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

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

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

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

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

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

print(str(ans))

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

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

s=0

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

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

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

Solution (Python):
num = int(input())
i=0
a=0
while i <= num:
    a += num-i
    i +=1
print(a)

Solution (Python):
num = int(input())
i=0
a=0
while i <= num:
    a += num-i
    i +=1
print(a)

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

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

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

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

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

Solution (Python):
url = "https://atcoder.jp/contests/abc043/tasks/abc043_a"

def main():

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

if __name__ == '__main__':
    main()

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

result = 0

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

print(result)

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

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

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

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

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):
a = int(input())
total = 0

for n in range(a+1):
    total += n
print(total)

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

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

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

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

ans = 0

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

print(ans)

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

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

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

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

ans = 0

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

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

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

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

Solution (Python):

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

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

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

Solution (Python):
import sys

n = int(sys.stdin.readline().rstrip())

def main():
    ans = (1 + n) * n // 2
    print(ans)

if __name__ ==  '__main__':
    main()

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

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

Solution (Python):

n = int(input())
print(sum(range(n + 1)))

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

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

print(total)

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

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

Solution (Python):
import sys
import copy
import math
import bisect
import pprint
import bisect
from functools import reduce
from copy import deepcopy
from collections import deque

if __name__ == '__main__':
    n = int(input())


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

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

Solution (Python):

import sys
sys.setrecursionlimit(10**8)
INF = float("inf")


def solve(N: int):
    print(N*(N+1)//2)
    return


def main():

    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  
    solve(N)


if __name__ == '__main__':
    main()

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

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

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

print(output)

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

print(count)

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

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

Solution (Python):
"""
in1 = ''
"""
in1 = input()

N = int(in1)
RC = 0

for idx1 in range(N):
    RC = RC + idx1 + 1

print(RC)

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

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

Solution (Python):
N=int(input())
sum=0
i=1
while i<=N:
  sum+=i
  i+=1
print(sum)

Solution (Python):


from queue import Queue
from queue import LifoQueue as Stack
from math import sqrt, floor, ceil, log2
from fractions import gcd
from itertools import permutations, combinations
from operator import itemgetter
from functools import cmp_to_key



__MOD__=(10**9)+7
yn = 'YNeos'
judge = False
cnt = 0
ans = None


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

def intinput():
    return int(input())

def mulinputs():
    return map(int,input().split())

def lineinputs(func=intinput):
    datas = []
    while True:
        try:
            datas.append(func())
        except EOFError:
            break
    return datas

class ModInt():
    def __init__(self, x):
        self.__x = (x % __MOD__)
    def __add__(self, other):
        if type(other) == int:
            other = self.__class__(other)
            return int(self.__class__((self.__x + other.__x)%__MOD__))
        elif type(other) == ModInt:
            return self.__class__((self.__x + other.__x)%__MOD__)
        else:
            raise Exception("Not Int or Not ModInt")
    def __sub__(self, other):
        if type(other) == int:
            other = self.__class__(other)
            return int(self.__class__((self.__x - other.__x)%__MOD__))
        elif type(other) == ModInt:
            return self.__class__((self.__x - other.__x)%__MOD__)
        else:
            raise Exception("Not Int or Not ModInt")
    def __mul__(self, other):
        if type(other) == int:
            other = self.__class__(other)
            return int(self.__class__((self.__x * other.__x)%__MOD__))
        elif type(other) == ModInt:
            return self.__class__((self.__x * other.__x)%__MOD__)
        else:
            raise Exception("Not Int or Not ModInt")
    def __truediv__(self, other):
        if type(other) == int:
            other = self.__class__(other)
            return int(self.__class__((self.__x * other.__modinv())%__MOD__))
        elif type(other) == ModInt:
            return self.__class__((self.__x * other.__modinv())%__MOD__)
        else:
            raise Exception("Not Int or Not ModInt")
    def __pow__(self, other):
        if type(other) == int:
            other = self.__class__(other)
            return int(self.__class__(pow(self.__x, other.__x, __MOD__)))
        elif type(other) == ModInt:
            return self.__class__(pow(self.__x, other.__x, __MOD__))
        else:
            raise Exception("Not Int or Not ModInt")
    def __modinv(self, m=__MOD__):
        a = self.__x
        if a == 0:
            raise ZeroDivisionError()
        if gcd(a, m) != 1:
            raise Exception("%sの逆数は求まりません。" % a)
        b, u, v = m, 1, 0
        while b != 0:
            t = a//b;
            a -= t*b
            a, b = b, a
            u -= t * v
            u, v = v, u
        u %= m
        if u < 0:
            u += m
        return u
    def __int__(self):
        return self.__x



if __name__ == '__main__':
    N = intinput()

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

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

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

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

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

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

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

sum1 = 0

for i in range(N + 1):
    sum1 = sum1 + i

print(sum1)

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

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 i in range(N):
    sum += (i + 1)

print(sum)

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

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

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

print(C)

Solution (Python):
x = int(input()) 
y = 0

for i in range(x+1):
    y += i 


print(y)

Solution (Python):
x = int(input()) 
y = 0

for i in range(x):
    y += i + 1


print(y)

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

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

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

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

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

def I(): return int(input())
def MI(): return map(int, input().split())
def LI(): return list(map(int, input().split()))

def main():
    mod=10**9+7
    N=I()
    print((N*(N+1))//2)

main()

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

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

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

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

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

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

Solution (Python):

N = int(input())

total = N*(N+1)/2
print(str(round(total)))

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

Solution (Python):


N = int(input().strip())


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

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

Solution (Python):

def f(x):
    if x<=1:
        return 1
    else:
        return f(x-1)+x
n=int(input())
print(f(n))

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

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

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

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

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

Solution (Python):

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

Solution (Python):
import sys
import itertools
readline = sys.stdin.buffer.readline

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

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

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

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

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())
k = N
for i in range (N):
    k = i + k
print(k)

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

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

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

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

print(ans)

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

Solution (Python):

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


if False:
    N=int(input())
    V=[int(i) for i in input().split()]
    K=list(set(V))
    if len(K)==1:
        print(N//2)
        exit()

    cnt={}
    cnt[-1]=0
    for k in K:
        cnt[k]=0
    for i in range(0,N,2):
        cnt[V[i]]+=1
    ev_MAX=0
    sec_ev_MAX=0
    ev=-1
    ev_cnt=[(cnt[k],k) for k in K]
    ev_cnt.sort(key=lambda x: x[0],reverse=True)
    ev=ev_cnt[0][1]
    ev_MAX=ev_cnt[0][0]
    sec_ev_MAX=0 if len(ev_cnt)<2 else ev_cnt[1][0]
    
    cnt={}
    cnt[-1]=0
    for k in K:
        cnt[k]=0
    for i in range(1,N,2):
        cnt[V[i]]+=1
    od_MAX=0
    sec_od_MAX=0
    od=-1
    od_cnt=[(cnt[k],k) for k in K]
    od_cnt.sort(key=lambda x: x[0],reverse=True)
    od=od_cnt[0][1]
    od_MAX=od_cnt[0][0]
    sec_od_MAX=0 if len(od_cnt)<2 else od_cnt[1][0]

    ans=0
    if od!=ev:
        
        ans+=N//2-ev_MAX
        ans+=N//2-od_MAX
    else:
        
        ans+=min(N//2-sec_ev_MAX+N//2-od_MAX,N//2-sec_od_MAX+N//2-ev_MAX)
    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())
print(n*(n+1)//2)

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

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

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


if __name__ == '__main__':
    main()

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

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

Solution (Python):
import sys

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

    return 0

if __name__ == "__main__":
    solve()

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

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

Solution (Python):
import sys, re, os
from collections import deque, defaultdict, Counter
from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians
from itertools import permutations, combinations, product, accumulate
from operator import itemgetter, mul
from copy import deepcopy
from string import ascii_lowercase, ascii_uppercase, digits
from fractions import gcd
def input(): return sys.stdin.readline().strip()
def STR(): return input()
def INT(): return int(input())
def MAP(): return map(int, input().split())
def S_MAP(): return map(str, input().split())
def LIST(): return list(map(int, input().split()))
def S_LIST(): return list(map(str, input().split()))
sys.setrecursionlimit(10 ** 9)
inf = sys.maxsize
mod = 10 ** 9 + 7

n = INT()
print(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+1):
    ans+=i
print(ans)

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

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

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

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

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

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

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())

cand = (1 + n)*n / 2

print(int(cand))

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

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

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

print(n)

Solution (Python):
n = int(input())
if n%2==0:
    result=(n+1)*n/2
else:
    m=int(n-1)
    result=(m+1)*m/2+n
print(int(result))

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

Solution (Python):
import sys

def I(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LMI(): return list(map(int, sys.stdin.readline().split()))
MOD = 10 ** 9 + 7


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

Solution (Python):
input1 = raw_input()

result = ((int(input1) + 1) * int(input1)) / 2

print result

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

Solution (Python):
if __name__ == '__main__':
    n = input()
    n = int(n)
    
    ans = sum(range(n+1))
    print(ans)

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

Solution (Python):
num = int(input())
sum = 0
for i in range(num+1):
    sum = 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((1+n) * (n/2)))

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

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

Solution (Python):
N=int(input())
C=[]
for n in range(N+1):
    C.append(n)
print(sum(C))

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

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

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

Solution (Python):

n = int(input())

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

Solution (Python):
n = input()
m = 0

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

Solution (Python):
N = int(input())
i=1
x=0
while i <= N:
    x += i 
    i += 1
print(x)

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
ame = 1
for i in range(n):
  ans+=ame
  ame+=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())
print(int((N + 1) * N / 2))

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

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

print(ans)

Solution (Python):
import sys, math

def input():
    return sys.stdin.readline()[:-1]

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

if __name__ == '__main__':
    main()

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

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

print(total)

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

print(total)

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


if __name__ == '__main__':
    main()

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

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

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

print(ans)

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

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

print(int(0.5 * n * (n+1)))

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

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

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

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

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

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

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

Solution (Python):
def souwa(num):
    sum = 0
    for i in range(num):
        sum += (i + 1)
    return sum


num = int(input())
answer = souwa(num)
print(answer)

Solution (Python):
def souwa(num):
    sum = 0
    for i in range(num):
        sum += (i + 1)
    return sum


num = int(input())
answer = souwa(num)
print(answer)

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

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

print(s)

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

print(sum(range(1, a + 1)))

Solution (Python):

 
 
def main():
 
    in_ninzu = int(input())
    
    
    in_candy = in_ninzu * (in_ninzu + 1) // 2
    
    print(in_candy)
  
    return 0
 
 
if __name__ == '__main__':
    main()

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

print(int(0.5 * a * (2 + (a - 1) * 1)))

Solution (Python):



N = int(input())

candy = 0
for n in range(N):
  candy += (n+1)
  
print(candy)

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(1, N + 1):
    ans += i
print(ans)

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

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

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

Solution (Python):

import sys


def solve(N: int):
    print(N * (N + 1) // 2)


def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  
    solve(N)


if __name__ == '__main__':
    main()

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

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


def func(x):
    if x == 1:
        return 1
    else:
        return func(x - 1) + x


print(func(N))

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

Solution (Python):
child=int(input())
ame=0

while child!=0:
    ame=ame+child
    child-=1

print(ame)

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

print(ans)

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

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

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

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

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

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

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

Solution (Python):

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

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

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

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

print(count)

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


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

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

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

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

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

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

resolve()

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

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

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

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