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

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

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

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

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

Solution (Python):

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

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

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

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

Solution (Python):
import math

n = int(input())

if n == 1:
    print(1)
elif n % 2 == 0:
    print((1 + n) * math.floor(n/2))
else:
    print((1 + n) * math.floor(n/2) + math.ceil(n/2))

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

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

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

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

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

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

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


if __name__ == '__main__':
    main()

Solution (Python):

"""
https://beta.atcoder.jp/contests/abc043/tasks/abc043_a

"""
import sys
from sys import stdin
input = stdin.readline


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


def main(args):
    N = int(input())
    ans = solve(N)
    print(ans)


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

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

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

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

Solution (Python):
import numpy as np

print(sum(np.arange(int(input())+1)))

Solution (Python):





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

if __name__ == "__main__": main()

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

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

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

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

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

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

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

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())

def addAll(n):
    if n == 1:
        return 1
    else:
        return addAll(n-1) + n

print(addAll(n))

Solution (Python):
print((int(input())*2+1)**2//8)

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

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

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

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

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

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

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

Solution (Python):
import math
def main():
    N = int(input())
    c = 0
    for x in range(N + 1): c += x
    print(c)


if __name__ == "__main__":
    main()

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

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

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

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

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

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

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

Solution (Python):
n = int(input()) + 1

num = 0

for i in range(n):
    num += i

print(num)

Solution (Python):

import math
import sys
import itertools
import numpy as np
import functools
import collections
mo = 1000000007
INF = 10**100
r = range

class infix(object):
    def __init__(self, function):
        self.function = function

    def __ror__(self, other):
        self.left = other
        return self

    def __or__(self, other):
        return self.function(self.left, other)

    def __call__(self, value1, value2):
        return self.function(value1, value2)

@infix
def c(f_t_u, f_u_r): return lambda t: f_u_r(f_t_u(t))

class _Ap(object):
    def __rlshift__(self, other):
        self.value = other
        return self

    def __rshift__(self, other):
        return other(self.value)
Ap = _Ap()
ap = Ap






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):



"""043-a"""


import sys


def main():
    """Main function."""
    N = int(input())
    print(sum(range(N+1)))


if __name__ == '__main__':
    sys.exit(main())

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

print(ans)

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

print(ans)

Solution (Python):
n = input()

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

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(n*-~n>>1)

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

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

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

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

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

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

Solution (Python):

a = int(input())
b = a * (a + 1) // 2;
print(b)

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):
from collections import defaultdict


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


if __name__ == '__main__':
    main()

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

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

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

ans = 0

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

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

C=int(N/2*(2+N-1))

print(C)

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

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

Solution (Python):
def ri(): return int(input())
def rli(): return list(map(int, input().split()))
def rls(): return list(input())
def pli(a): return "".join(list(map(str, a)))

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

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

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

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

print(x)

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

Solution (Python):
def ini(): return int(input())
def inli(): return list(map(int, input().split()))
def inf(): return float(input())
def inlf(): return list(map(float, input().split()))
def inl(): return list(input())
def pli(): return "".join(list(map(str, ans)))

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

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

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

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

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

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

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

Solution (Python):
N = 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())
sum = 0

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

print(sum)

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

print(sum)

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

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

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

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

main()

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

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

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

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

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

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

Solution (Python):

input = int(raw_input())
count = 0
for i in range(1, input+1):
 count += i
print count

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

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

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

Solution (Python):
import sys

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

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


if __name__ == '__main__':
    solve()

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

Solution (Python):


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

if __name__=="__main__":
    main()

Solution (Python):

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

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

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

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

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

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

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

Solution (Python):


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

Solution (Python):
def fun(x):
    return x if x==1 else x+fun(x-1)

print(fun(int(input())))

Solution (Python):



N = int(input())

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

Solution (Python):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time

sys.setrecursionlimit(10**7)
inf = 10**20
mod = 10**9 + 7


def main():
    n = int(input())
    return int(n*(n+1) // 2)



print(main())

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

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

Solution (Python):


def arithmetic_series(a, d, n):
    return n * (2 * a + (n - 1) * d) // 2


def main():
    n = int(input())
    print(arithmetic_series(1, 1, n))


if __name__ == '__main__':
    main()

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


if __name__ == '__main__':
    main()

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

Solution (Python):
N = input()
i = 0
a = 0


while(i<=N):
    a = a + i

    i = i+1

print(a)

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

print(a)

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

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

Solution (Python):


 

input = input() 
 
sum = 0
for num in range(1,int(input) + 1):
	sum += num;
print(sum)

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

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

Solution (Python):
def calc(n):
	return n * (n+1) / 2

def main():
	n = int(raw_input())
	print calc(n)

main()

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

print N * (N+1) / 2

Solution (Python):
N = int(raw_input())
ans = 0
for n in xrange(1, N+1):
    ans += n
print ans

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

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

print(answer)

Solution (Python):

import sys,copy,math,heapq,itertools as it,fractions,re,bisect,collections as coll

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

Solution (Python):
def read():
    return int(input())

def reads(sep=None):
    return list(map(int, input().split(sep)))

def main():
    n = read()
    print(sum([i+1 for i in range(n)]))

main()

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

Solution (Python):
n = input()

print n * (n + 1) / 2

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

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

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

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

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

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

Solution (Python):
N=input()

print N*(N+1)/2

Solution (Python):


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

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

sum = 0

for i in xrange(N+1):
     sum += i

print sum

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

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

Solution (Python):
from sys import stdin, stdout

n = int(stdin.read().strip())

result = str(int(n * (n + 1) / 2))

stdout.write(result)

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

n=0

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

print n

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Solution (Python):
import sys


N = int(raw_input())

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

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

Solution (Python):

import sys
     
n = int(raw_input())
     
print n*(n+1)/2

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

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

Solution (Python):



n=int(raw_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(raw_input())
print N * ( N + 1 ) / 2

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

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

print ans

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

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

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

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

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

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

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

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

Solution (Python):
def fact(n):
   if n == 0: return 0
   return n + fact(n-1)

def main():
    a = int(raw_input())
    print fact(a)
    
if __name__ == '__main__':
    main()

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

Solution (Python):

x = int(input())

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

Solution (Python):
ans = 0

N = int(input())

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

print(ans)

Solution (Python):


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

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

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

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

Solution (Python):


import functools


n = int(input())
answer = functools.reduce(lambda x, y: x + y, range(1, n+1))
print(answer)

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

Solution (Python):
def solve(N):
 return N * (N + 1) // 2 

print(solve(int(input())))

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

s = n*( n+1)/2

print s

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

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

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

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

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

print sum

Solution (Python):
n=int(raw_input())
print (1+n)*(n/2) if n%2==0 else (1+n)*(n/2)+(1+n)/2

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

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

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

Solution (Python):
a = input()
a += 1
s = 0

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

print s

Solution (Python):


print(sum(x for x in range(1, int(input())+1)))

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

Solution (Python):
import re
import doctest

class IO_for_Contest(object):
    @staticmethod
    def my_input():
        
        return input()

    @staticmethod
    def read_from_input():
        
        pass

    @staticmethod
    def read_line():
        return IO_for_Contest.my_input().strip()

    @staticmethod
    def read_int():
        return int(IO_for_Contest.my_input().strip())

    @staticmethod
    def read_n_int(n):
        return list(map( \
                int, \
                re.split('\s+', IO_for_Contest.my_input().strip())))[ : n]
def solve():
    n = IO_for_Contest.read_int()
    print(int(n * (n + 1) / 2))

if __name__ == '__main__':
    
    solve()

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

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

print sum

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

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

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

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

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