211128

'''
# 사이의 홀수를 출력하기
def rec(a,b):
    if a > b :
        return

    if a%2==1:
        print(a, end = ' ')
    rec(a+1,b)


a,b = map(int,input().split())

rec(a,b)

#n 까지 의 합 출력
import sys
sys.setrecursionlimit(1000000000)

def rec(n):
    if n==1:
        return 1

    return n+rec(n-1)

n=int(input())
print(rec(n))

#피보나치 수열
def fibo(n):
 if n == 0:
        return 0
 elif n == 1:
        return 1
 else:
    return fibo(n-1) + fibo(n-2)
n=int(input())
print(fibo(n))
#피보나치 라지
import sys
sys.setrecursionlimit(1000000000)

memo = [0]*1000000

def fibo(n):
    if n <= 2:
        memo[n] = 1
        return memo[n]

    if memo[n]!=0:
        return memo[n]

    memo[n] = (fibo(n-1)%10009 + fibo(n-2)%10009)%10009
    return memo[n]

n=int(input())
print(fibo(n)%10009)

import sys
sys.setrecursionlimit(1000000000)


def ubs(n):

    if n == 1 :
        print(n)
        return

    elif n % 2 == 1:
        print(n)
        ubs((3 * n) + 1)


    elif n % 2 == 0:
        print(n)
        ubs(n // 2)



x=int(input())
ubs(x)
'''

'''
import sys
sys.setrecursionlimit(1000000000)

memo = [0]*1000000

def gd(n):
    if n == 2:
        memo[n] = 2
        return memo[n]

    if n == 3:
        memo[n] = 4
        return memo[n]

    if n == 1:
        memo[n] = 1
        return memo[n]

    if memo[n] != 0:
        return memo[n]

    if  n > 2:
        memo[n] = (gd(n-3)+gd(n-2)+gd(n-1))%1000
        return memo[n]

n=int(input())
print(gd(n))


class model:
    dataX = 0
    dataY = 0
    def __init__(self, x, y):
        self.dataX = x
        self.dataY = y
        self.change()
        self.calcuSum()

    def change(self):
        self.dataX = int(self.dataX)
        self.dataY = int(self.dataY)

    def calcuSum(self):
        v = self.dataX + self.dataY
        return v
        #self.printWindow(v)

    def printWindow(self, t):
        print(t)

a, b = input().split()

x = model(a, b)
x.printWindow(x.calcuSum())
'''