peterverebics/CodeNet_Python_118 huggingface dataset:
import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 7)

n = int(input())

def binary_search(n):
    ok = n
    ng = 0
    while abs(ok - ng) > 1:
        mid = (ok + ng) // 2
        if (mid * 1.08) >= n:
            ok = mid
        else:
            ng = mid
    return ok

ans = binary_search(n)
if int(ans * 1.08) == n:
    print(ans)
else:
    print(':(')
import math
price = int(input())
tax = 8
price_1 = math.ceil(price / (1 + tax / 100))
price_2 = math.floor(price_1 * tax / 100)
print(price_1 if price == price_1 + price_2 else ':(')
import sys
from collections import deque
import numpy as np
import math
sys.setrecursionlimit(10**6)
def S(): return sys.stdin.readline().rstrip()
def SL(): return map(str,sys.stdin.readline().rstrip().split())
def I(): return int(sys.stdin.readline().rstrip())
def IL(): return map(int,sys.stdin.readline().rstrip().split())

def solve():
    f = math.ceil(n/1.08)
    if math.floor(f*1.08)==n:
        print(f)
    else:
        print(':(')
    return

if __name__=='__main__':
    n = I()
    solve()
n = int(input())
for i in range(1,n+1):
    if int(i*1.08) == n:
        print(i)
        break
else:
    print(":(")
import sys
def I(): return int(sys.stdin.readline().rstrip())

N = I()
for i in range(50000):
    if i*27//25 == N:
        print(i)
        break
else:
    print(':(')
#解説AC
n = int(input())
for i in range(50001):
    if int(i*1.08) == n:
        print(i)
        exit()
print(":(")
N=int(input())
import math
X=math.ceil(N/1.08)
if int(X*1.08)==N:
    print(X)
else:
    print(':(')
N = int(input())
# N <= X x 1.08 < N+1
# になる整数Xを求める

# min_xとmax_xの間に1つでも整数が存在していればいい
import math
min_x = math.ceil(N/1.08)
max_x = math.ceil((N+1)/1.08)
if max_x - min_x >= 1:
    print(min_x)
else:
    print(':(')
import math
N = int(input())
A = []
I = []
cnt=0

for i in range(50000):
  I.append(i)
  A.append(math.floor(1.08*i))

for i in range(len(A)):
  if A[i]==N:
    cnt+=i

if cnt!=0:
  print(cnt)
elif cnt==0:
  print(':(')
import math

N = int(input())

ans = int(-(-N // 1.08))

if math.floor(ans * 1.08) == N:
	print(ans)
else:
	print(":(")
import math
n = int(input())
li = []
for i in range(1, 50001):
    li.append(math.floor(i * 1.08))
if n in li:
    print(math.ceil(n/1.08))
else:
    print(':(')
import numpy as np

n = int(input())
x = np.ceil(n/1.08)
if np.floor(x * 1.08) == n:
  print(int(x))
else:
  print(":(")
# coding: utf-8
import math
N = int(input())

ans = int(N // 1.08 + 1)

if N == int(ans * 1.08):
    print(ans)
else:
    print(":(")
# -*- coding: utf-8 -*-
import math

N = int(input())

for x in range(N,0,-1):
    val = int(x * 1.08)
    if val == N:
        print(x)
        exit()

print(':(')
N = int(input())
for i in range(1, 50000):
    if int(i*1.08) == N:
        print(i)
        break
    elif int(i*1.08) > N:
        print(":(")
        break
import sys

readline = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = float('INF')
sys.setrecursionlimit(10 ** 5)


def main():
    N = int(readline())

    def solve():
        for i in range(100001):
            cur = i * 108 // 100
            if cur == N:
                return i
        return ":("

    print(solve())


if __name__ == '__main__':
    main()
import math

n = int(input())
ans = -1

for i in range(1, n+1):
    if math.floor(i * 1.08) == n:
        ans = i

if ans != -1:
    print(ans)
else:
    print(":(")
import math
n = int(input())
result = math.ceil(n / 1.08)
print(result) if math.floor(result * 1.08) == n else print(":(")
import math
N = int(input())
zeinuki = math.floor(N / 1.08)
if N != math.floor(zeinuki * 1.08):
  if N != math.floor((zeinuki + 1) * 1.08):
    print(':(')
  else:
    print(zeinuki + 1)
else:
  print(zeinuki)
n=int(input())
a=n/1.08
if a==int(a):
    b=a
else:
    b=int(a)+1
if int(b*1.08)==n:
    print(int(b))
else:
    print(':(')
n = int(input())
for i in range(50001):
    if int(i*1.08) == n:
        print(i)
        exit()
print(":(")
n = int(input())
ans = int(n / 1.08)
if int(ans * 1.08) != n:
  ans = int(n / 1.08) + 1
  if (int(ans * 1.08)) != n:
    ans = ':('
print(ans)
import sys
input=sys.stdin.buffer.readline
N=int(input())
tax=27/25
for i in range(1,N+1):
    money=int(i*tax)
    if money==N:
        print(i)
        exit(0)
print(":(")
import math

N = int(input())
for x in range(N + 1):
    if x * 108 // 100 == N:
        print(x)
        break
else:
    print(':(')
ni = lambda: int(input())
nm = lambda: map(int, input().split())
nl = lambda: list(map(int, input().split()))

from math import floor

n=ni()

for i in range(n+1):
  if floor(i*1.08)==n:
    print(i)
    exit()
print(':(')
import math
def resolve():
    n=int(input())
    x=math.ceil(n/1.08)
    if n==math.floor(x*1.08):
        print(x)
    else:
        print(':(')
resolve()
n = int(input())

price = []

for i in range(1, 50000):
    p = int(i*1.08)
    price.append(p)

for i, p in enumerate(price):
    if p==n:
        print(i+1)
        exit()

print(':(')
N = int(input())

a = int(N/1.08)

for i in range(a-1, a+2):
    if int(i*1.08) == N:
        result = i
        break
else:
    result = ":("

print(result)
from math import floor
n = int(input())

for x in range(n+1):
    cost = floor(x * 1.08)
    if cost == n:
        print(x)
        exit()
print(":(")
from sys import exit
N = int(input())
for x in range(1, 50001):
    if int(x * 1.08) == N:
        print(x)
        exit(0)
print(":(")
N=int(input())
X=int(N//1.08)
n1=int(X*1.08)
n2=int((X+1)*1.08)
if n1==N:
    print(X)
elif n2==N:
    print(X+1)
else:
    print(':(')
import math
n = int(input())
x = int(n/1.08)

if math.floor(x*1.08) == n:
    print (x)
elif math.floor((x-1)*1.08) == n:
    print (x-1)
elif math.floor((x+1)*1.08) == n:
    print (x+1)
else:
    print (":(")
N = int(input())
for x in range(1,100000):
  if x*108//100==N:
    print(x)
    break
if x==99999:
  print(":(")
import math
N = int(input())

min = math.floor(N / 1.08)
max = math.ceil(N/ 1.08)
flag = False
for i in range(min,max+1):
    ans = math.floor(i*1.08)
    if N == ans:
        X = i
        flag = True
        break
if(flag):
    print(X)
else:
    print(':(')
N = int(input())
 
for i in range(0,N+1):
    if int(i*1.08)==N:
      print(i)
      exit()
print(":(")
import math, sys
N = int(input())
p = [int(N/1.08), math.ceil(N/1.08)]

for n in p:
    if int(n*1.08)==N:
        print(n)
        sys.exit()

print(":(")
import math
n=int(input())
ans=-1
for x in range(0,50000):
  if n==math.floor(x*1.08):
    ans=x
    break
if ans==-1:
  print(":(")
else:
  print(ans)
n = int(input())
xtest = int(n//1.08)

if n <= xtest*1.08 < n+1:
    print(xtest)
elif n<= (xtest+1)*1.08 < n+1:
    print(xtest+1)
else:
    print(":(")
import math

N = int(input())

ret = ':('
for i in range(50000):
    if N == math.floor(i * 1.08):
        ret = i

print(ret)
N = int(input())
k = 0
import math
for i in range(1, N+1):
    if math.floor(i*1.08) == N:
        print(i)
        k = 1
        break
if k ==0 :
    print(':(')
import math
n=int(input())
a_min=n/1.08
a_max=(n+1.0)/1.08
#print(a_min,a_max)
ans=a_min

if (math.ceil(a_min)<math.ceil(a_max)):
    print(math.ceil(a_min))
else:
    print(":(")
N = int(input())
C =  int(N/1.08)
flag = False
for i in range(0, 2):
    if int((C+i)*1.08) == N:
        print(C+i)
        flag = True
if not flag:
    print(":(")
n = int(input())
rate = 1.08

x = int(n / rate)
r = int(x * rate)
l = int((x + 1) * rate)
if n == r:
    print(x)
elif n == l:
    print(x + 1)
else:
    print(":(")
N=int(input())
P,Q=108,100

A=(N*Q+P-1)//P
B=((N+1)*Q+P-1)//P-1

if A>B:
    print(":(")
else:
    print(A)
N = int(input())
for i in range(50000):
  if N <= i*1.08 < N + 1:
    print(i)
    break
else:
  print(":(")
n=int(input())

ans=-1
for i in range(1,n+1):
  if int(i*1.08)==n:
    ans=i

if ans!=-1:
  print(ans)
else:
  print(":(")
import math
N = int(input())
ans = math.ceil(N // (1.08))

while math.floor(ans*1.08) < N:
  ans += 1
  if math.floor(ans*1.08) == N:
    print(ans)
  elif math.floor(ans*1.08) > N:
    print(':(')
import sys
input=sys.stdin.readline
n=int(input())
v=n*100//108
for i in range(min(0,v-100),v+100):
    if i*108//100==n:print(i);break
else:print(":(")
N = int(input())
for i in range(1, N+1):
    if int(i * 1.08) == N:
        print(i)
        exit()
print(":(")
# coding: utf-8
# Your code here!
#from sys import stdin
#import math
#from functools import reduce
    
#A, B, C = [int(x) for x in stdin.readline().rstrip().split()]
N = int(input())
#S = list(input())
 
#is_exist = 'Yes'

n = int(N / 1.08)
out = str(n)
#print(N/1.08)
#
if (n*1.08) < N:
    out = ':('
    
if ((n+1)*1.08) < N+1:
    out = str(n+1)

print(out)
n = int(input())
N = int(n/1.08)
for i in range(3):
    if int((N + i) * 1.08) == n:
        print(N+i)
        break
else:
    print(':(')
n = int(input())
for i in range(int(n * (25 / 27)), int(n * (25/ 27) + 3)):
    if int(i * 1.08) == n:
        print(i)
        exit()
print(":(")
import sys
n = int(input())
ans = n*100/108
for i in [int(ans), int(ans)+1]:
    if int(i*1.08) == n:
        print(i)
        sys.exit()
print(":(")
import math

N = int(input())
x = int(math.ceil(N / 1.08))
if int(x * 1.08) == N:
    print(x)
else:
    print(':(')
N = int(input())
X = -(-N//1.08)
n = X*108//100
if(int(N)==int(n)):
  print(int(X))
else:
  print(':(')
import math

N = int(input())
i = 0

while(i <= 50000):
    if math.floor(i * 1.08) == N:
        print(i)
        break
    i += 1
else:
    print(":(")
import sys
N=int(input())
a=N//1.08
c=a+1
d=a-1
b=a*1.08
b=int(b)
if b==N:
  print(int(a))
  sys.exit()
elif int(c*1.08)==N:
  print(int(c))
elif int(d*1.08)==N:
  print(int(d))
else:
  print(":(")
import math
N = int(input())
flag = 0
for i in range(1,54001):
    if math.floor(i*1.08) == N:
        print(i)
        flag += 1
        break
if flag == 0:
    print(":(")
N = int(input())

X = N / 1.08

X_down = int(X)
X_up = int(X) + 1

bool_down = int(X_down * 1.08) == N
bool_up = int(X_up * 1.08) == N

if bool_down:
    print(X_down)
elif bool_up:
    print(X_up)
else:
    print(":(")
import math

N = int(input())

fl = math.floor(N / 1.08)
cl = math.ceil(N / 1.08)

if math.floor(fl * 1.08) == N:
    print(fl)
elif math.floor(cl * 1.08) == N:
    print(cl)
else:
    print(":(")
N = int(input())

Ndict={}
for i in range(50000):
    price=int(i*1.08)
    Ndict[price]=i

if N in Ndict.keys():
    print(Ndict[N])
else:
    print(":(")
N = int(input())
X = int(N//1.08)+1

if int(X*1.08) == N:
  print(X)
else:
  print(':(')
#!/usr/bin/env python3

# from numba import njit

# from collections import Counter
# from itertools import accumulate
# import numpy as np
# from heapq import heappop,heappush
# from bisect import bisect_left

# @njit
def solve(n):
  for x in range(50000):
    if x * 108 // 100 == n:
      return x
  return ":("



def main():
  N = int(input())
  # N,M = map(int,input().split())
  # a = list(map(int,input().split()))
  print(solve(N))
  return

if __name__ == '__main__':
  main()
n = int(input())
a = int(n//1.08)
for x in range(a, a+2):
  if x < (n + 1)/1.08 and x >= n/1.08:
    print(x)
    exit()
print(':(')
N = int(input())

for i in range(1,N+1):
  if int(i*1.08) == N:
    print(i)
    exit()
else:
  print(':(')
n = int(input())

for x in range(1,50001):
    if x*1.08//1 == n:
        print(x)
        exit()
    
print(":(")
def readinput():
    n=int(input())
    return n

def main(n):
    x7=int(n/1.07)
    x8=int(n/1.08)
    x9=int(n/1.09)
    n100=n*100
    for x in range(max(1,x9-1),x7+1+1):
        xx=x*108//100
        #print(x,xx)
        if xx==n:
            print(x)
            break
    else:
        print(':(')

        

if __name__=='__main__':
    n=readinput()
    main(n)
n=int(input())
m=round(n/1.08)
if int(m*1.08)==n:
  print(m)
  exit()
else:
  if int((m-1)*1.08)==n:
    print(m-1)
    exit()
  elif int((m+1)*1.08)==n:
    print(m+1)
    exit()
  else:
    print(':(')
    exit()
N=int(input())
flg=False
ans=0
for n in range(1, N+1):
  if (int(1.08*n) == N):
    ans=n
    flg=True
if flg:
  print(ans)
else:
  print(':(')
from decimal import Decimal, ROUND_HALF_UP, ROUND_HALF_EVEN

import math

N = int(input())

X = N / 1.08
# X = Decimal(str(X)).quantize(Decimal('0'), rounding=ROUND_HALF_UP)

X = int(math.ceil(X))

if N == int(X * 1.08):
  print(X)
else:
  print(':(')
N = int(input())

price = int(N / 1.08)

if int(price * 1.08) == N:
    print(price)
elif int((price + 1) * 1.08) == N:
    print(price + 1)
else:
    print(":(")
N = int(input())
t = int(N/1.08)
if(t*1.08 == N):
    print(t)
elif(int((t+1)*1.08) == N):
    print(t+1)
elif(int((t-1)*1.08) == N):
    print(t-1)
else:
    print(':(')
N = int(input())

for i in range(N+1):
    if int(i * 1.08) == N:
        print(i)
        exit(0)
else:
    print(":(")
import math

N = int(input())

if (N+1) % 27 == 0 or (N+14) % 27 == 0:
    print(':(')
else:
    print(math.floor((N+0.99)/1.08))
N = int(input())

for i in range(1, 50000):
    pay = int(i*1.08)
    if pay == N:
        print(i)
        break
    elif pay > N:
        print(':(')
        break
import sys
import itertools
# import numpy as np
import time
import math
import heapq
from collections import defaultdict
from collections import Counter
sys.setrecursionlimit(10 ** 7)
 
INF = 10 ** 18
MOD = 10 ** 9 + 7
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

# map(int, input().split())

N = int(input())
for x in range(1, N + 1):
    val = x * 108
    val -= val % 100
    if val == N * 100:
        print(x)
        exit()
print(":(")
N = int(input())
C = N * 100 // 108
C_l = [C - 1, C, C + 1]
for c in C_l:
    c_ = c * 108 // 100
    if c_ == N:
        print(c)
        break
else:
    print(':(')
from sys import stdin
import math
N = int(stdin.readline().rstrip())

for i in range(1, 50000):
  if math.floor(i * 1.08) == N:
    print(i)
    exit()
print(":(")
import math
N = int(input())
TAX = 1.08
a = math.ceil(N / TAX)
print(a) if math.floor(a * TAX) == N else print(":(")
import math
N = int(input())

X = N / 1.08

if X.is_integer():
    print(int(X))
else:
    if math.floor(math.ceil(X) * 1.08) == N:
        print(math.ceil(X))
    else:
        print(':(')
import math

zeikomi = int(input())
zeinuki_mae = zeikomi / 1.08
zeinuki = math.ceil(zeinuki_mae)
zeikomi_ato = math.floor(zeinuki * 1.08)

if zeikomi != zeikomi_ato:
    print(':(')
else:
    print(zeinuki)
N = int(input())
origin = N * 100 // 108
if int(origin * 1.08) == N:
    print(origin)
elif int((origin + 1) * 1.08) == N:
    print(origin + 1)
else:
    print(":(")
from math import floor
n = int(input())
ans = [i for i in range(50000) if floor(i*1.08) == n]
print(ans[0] if ans else ':(')
import math
N = int(input())
result = float(N) / 1.08
result_int_floor = math.floor(result)
result_int_ceil = math.ceil(result)
if(math.floor(result_int_floor * 1.08) == N):
    print(result_int_floor)
elif(math.floor(result_int_ceil * 1.08) == N):
    print(result_int_ceil)
else:
    print(":(")
n = int(input())

for i in range(1,n+1):
  x = i * 108
  x //= 100
  if x == n:
    print(i)
    exit()
print(":(")
end_price = int(input())
price = end_price/1.08
price = int(price)

start_price = [price, price+1, price-1]
prices = [int(price*1.08), int((price+1)*1.08), int((price-1)*1.08)]

for ind, x in enumerate(prices):
    if x == end_price:
        print(start_price[ind])
        exit(0)
print(":(")
import math
a = int(input())
for i in range(50001):
    if math.floor(i*1.08) == a:
        print(i)
        exit()
print(":(")
n = int(input())
c=0
for i in range(50000):
  if int(i * 1.08) == n:
    print(i)
    c = 1
    break
if c == 0:
  print(":(")
def main():
    N = int(input())
    for i in range(1,50000):
        if int(i * 1.08) == N:
            print(i)
            exit()
        
    print(':(')



if __name__ == "__main__":
    main()
N = int(input())

est_X = int(N/1.08)

if int(est_X*1.08) == N:
    print(est_X)
elif int((est_X + 1)*1.08) == N:
    print(est_X + 1)
else:
    print(':(')
n = int(input())

for i in range(0,n+1):
  if(int(i*1.08) == n):
    print(i)
    exit()
  else:
    continue
print(":(")
n=int(input())
for x in range(n+1):
    if int(x*1.08)==n:
        print(x)
        exit()
print(":(")
n = int(input())
mi = n / 1.08
ma = (n+1) / 1.08
tar = int(mi)
while(tar <= ma):
    if mi <= tar < ma:
        print(tar)
        quit()
    tar += 1
print(":(")
def resolve():
    n=int(input())
    ans=(':(')
    for i in range(1,n+1):
        if int(i*1.08)==n:
            ans=i
    print(ans)
resolve()
# -*- coding: utf-8 -*-
import numpy as np
import sys
from collections import deque
from collections import defaultdict
import heapq
import collections
import itertools
import bisect
from scipy.special import comb
import copy
sys.setrecursionlimit(10**6)


def zz():
    return list(map(int, sys.stdin.readline().split()))


def z():
    return int(sys.stdin.readline())


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


def C(line):
    return [sys.stdin.readline() for _ in range(line)]


N = z()
min_ = int((N//1.08)-1)
for v in range(min_, min_+100):
    if (int(v * 1.08) == N):
        print(v)
        exit()

print(':(')
import math
i = int(input())
ans = math.ceil(i / 1.08)
if math.floor(ans*1.08) == i: 
	print(ans)
else:
	print(":(")
import math
n=int(input())
ans=math.ceil(n/1.08)
if int(ans*1.08)==n:
    print(ans)
else:
    print(":(")
import math

N=int(input())

for i in range(1,N+1):
	if math.floor(i*1.08)==N:
		print(i)
		exit()
print(":(")
#N <= 1.08 * X < N + 1
import math as m
N = int(input())

k = N / 1.08
k = round(k)

if m.floor(k * 1.08) == N:
    print(k)
elif m.floor((k-1) * 1.08) == N:
    print(k-1)
elif m.floor((k+1) * 1.08) == N:
    print(k+1)
elif m.floor((k-2) * 1.08) == N:
    print(k-2)
elif m.floor((k+2) * 1.08) == N:
    print(k+2)
else:
    print(':(')
N = int(input())

ans = 0
for i in range(49999):
    if int(i*1.08) == N:
        ans = i

if ans:
    print(ans)
else:
    print(":(")
def n_cand(x):
    return int(x*1.08)

n = int(input())

x = round(n / 1.08)
n_dash = n_cand(x)
n_dash_m = n_cand(x-1)
n_dash_p = n_cand(x+1)
if n_dash == n:
    print(x)
elif n_dash_m == n:
    print(x-1)
elif n_dash_p == n:
    print(x+1)
else:
    print(':(')
N = int(input())

for i in range(50000):
    if int(i*1.08) == N:
        print(i)
        exit()

print(":(")
n = int(input())
ans = 0
for i in range(1, n+1):
    if int(i * 1.08) == n:
        ans = i

if ans == 0:
    print(":(")
else:
    print(ans)
import math

# Input the amount of money Takahashi paid
N = int(input())

# Find nearest integer price more than or equal to X/1.08
X = math.ceil(N / 1.08)

# Check if the "taxed price" is equal to N yen
if math.floor(X * 1.08) == N:
	print(X)
else:
	print(":(")
from math import ceil,floor
N=int(input())
K=ceil(N/1.08)
if floor((K-1)*1.08)==N:
  print(K-1)
if floor(K*1.08)==N:
  print(K)
else:
  print(':(')
n = int(input())
result = ":("
for i in range(1, 50001):
    if int(i*1.08)==n:
        result = i
        break
print(result)
import math
N=int(input())
price=math.ceil(N/1.08)
print(price if int(price*1.08)==N else ":(")
from math import floor, ceil

N = int(input())

def g(x):
    return ceil(x*100/108)

def v(x):
    return floor(x*1.08)

expected_X = g(N)
value = v(expected_X)

if N == value:
    print(expected_X)
else:
    print(":(")
n = int(input())
import math
for i in range (50000):
  x = i*1.08
  if math.floor(x) == n:
    print(i)
    exit()
print(":(")
import math

n = int(input())
price = math.ceil(n/1.08)

print(price if math.floor(price*1.08) == n else ':(')
n = int(input())
f = int(n/1.08)
a = True
for i in range(f-5,f+5):
    if int(i * 1.08)==n:
        print(i)
        a = False
        break
if a:
    print(':(')
n=int(input())
res=0

for i in range(1,n+1):
    if int(i*1.08)==n:
        res=i
if res != 0:
    print(res)
else:
    print(":(")
N = int(input())
Y = int(N/1.08)
a = Y
b = Y+1
if int(a*1.08) == N:
  print(a)
elif int(b*1.08) == N:
  print(b)
else:
  print(':(')
N = int(input())
original = int(N // 1.08)

if 0 <= (original * 1.08) - N < 1:
  print(original)
elif 0 <= ((original + 1) * 1.08) - N < 1:
  print(original + 1)
else:
  print(':(')
N = int(input())
X = N//1.08-1
while True:
    a = int(X*1.08)
    if a == N:
        print(int(X))
        exit()
    elif a < N:
        X += 1
    else:
        print(':(')
        exit()
import sys

sys.setrecursionlimit(10 ** 8)
ini = lambda: int(sys.stdin.readline())
inl = lambda: [int(x) for x in sys.stdin.readline().split()]
ins = lambda: sys.stdin.readline().rstrip()


def solve():
    n = ini()
    for x in range(n + 1):
        y = int(x * 1.08 + 1e-8)
        if y == n:
            return x
    return ":("


print(solve())
n = int(input())
ans = int(n / 1.08)
if int(ans * 1.08) == n:
    print(ans)
else:
    ans2 = ans + 1
    if int(ans2 * 1.08) == n:
        print(ans2)
    else:
        print(':(')
N = int(input())
import math
a = math.ceil(N/1.08-1)
ans=':('
if int((a+1)*1.08)==N:
  ans = a+1

print(ans)

#print(*ans, sep='/n')
n = int(input())
f = 0
for i in range(1, n+1):
  if int(i*1.08) == n:
    print(i)
    exit()
print(':(')
def solve():
    N = int(input())
    
    ans = int(N * 100 / 108)
    if int(ans * 1.08) == N:
        print(ans)
    elif int((ans + 1) * 1.08) == N:
        print(ans + 1)
    else:
        print(':(')


if __name__ == '__main__':
    solve()
import math
N = int(input())
flag = True
for i in range(N+1):
    if math.floor(i * 1.08) == N:
        print(i)
        flag = False
        break
if flag:
    print(':(')
n=int(input())
if (((n/1.08)//1)*1.08)//1==n:
    print(int((n/1.08)//1))
elif (((n/1.08)//1+1)*1.08)//1==n:
    print(int(((n+1)/1.08)//1))
else:
    print(":(")
N=int(input())
for i in range(N+1):
  if int(i*1.08)==N:
    print(i)
    exit()
print(":(")
n = int(input())
for i in range(50000):
    if int(i*1.08)==n:
        print(i)
        break
else:
    print(':(')
N=int(input())
x=N//1.08
if int(x*1.08) == N:
  print(int(x))
elif int((x+1)*1.08) == N:
  print(int(x+1))
else:
  print(':(')
import math
def main2():
    n = int(input())
    x = int(math.ceil(n / 1.08))
    
    if int(x*1.08) == n:
        print(x)
    else:
        print(":(")

if __name__ == "__main__":
    main2()
import math
N = int(input())
price = math.ceil(N/1.08)
if math.floor(price*1.08) == N:
    print(price)
else:
    print(':(')
n = int(input())
for i in range(50001):
    if int(i*1.08) == n:
        print(i)
        exit()
        
print(":(")
X = int(input())
import math
ans = math.floor(math.ceil(X/1.08))

if math.floor(math.ceil(X/1.08)*1.08) != X:
  print(":(")
else:
  print(ans)
N = int(input())
for i in range(1,50001):
    intax = int(i * 1.08)
    if intax == N:
        print(i)
        exit()
print(":(")
import math
N = int(input())
if int(math.ceil(N/1.08)*1.08) == N:
    print(math.ceil(N/1.08))
else:
    print(':(')
n = int(input())
for i in range(1,n+1):
    ans = int(i*1.08)
    if ans == n:
        print(i)
        break
else:
    print(":(")
n=int(input())
for i in range(1,n+1):
    if int(i*1.08) == n:
        print(i)
        exit()

print(':(')
N = int(input())
X = N//1.08 + 1
ans = int(X*1.08)
if ans == N:
    print(int(X))
else:
    print(':(')
import math

n = int(input())

for price in range(1, 50001):
    if math.floor(price*1.08) == n:
        print(price)
        exit()
print(":(")
import sys
input = sys.stdin.readline
sys.setrecursionlimit(10 ** 7)

n = int(input())

def bs(ok, ng, solve):
    while abs(ok - ng) > 1:
        mid = (ok + ng) // 2
        if solve(mid):
            ok = mid
        else:
            ng = mid
    return ok

ok = n
ng = 0
ans = bs(ok, ng, lambda x: x * 1.08 >= n)
if int(ans * 1.08) == n:
    print(ans)
else:
    print(':(')
import math

N = int(input())
rate = 1.08
# print((N / rate))
# print((N + 1) / rate)
a = math.ceil(N / rate)
b = math.ceil((N + 1) / rate)
# print(a)
# print(b)
if a >= b:
    print(":(")
else:
    # assert math.floor(a * rate) == N
    print(a)
n = int(input())
for i in range(1,n+1):
  if(int(i*1.08) == n):
    print(i)
    exit()
print(":(")