Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func main() {
	sc.Scan()
	F, _ := strconv.Atoi(sc.Text())
	fmt.Println((F - 30) /2)
}

Python: F = int(input())
print((F-30)//2)

Python: f=int(input())
c=int((f-30)/2)
print(c)

Python: F=int(input())
C=(F-30)//2
print(C)

Python: f = int(input())
print((f-30)//2)

Python: F=int(input())
C=int((F-30)/2)
print(C)

Python: F=int(input())
print(int((F-30)/2))

Python: F = int(input())
print((F-30)//2)

Python: f = int(input())
c = (f - 30) // 2
print(c)

Python: f=int(input())
print((f-30)//2)

Python: F = int(input())
print((F-30)//2)

Python: import math
F = int(input())
print(math.floor((F - 30) / 2))

Python: F=int(input())
print((F-30)//2)

Python: # coding: utf-8
# Your code here!

F=int(input())
A = int((F-30)/2)
print('%d'%A)

Python: F = int(input())
print(int((F-30)/2))

Python: F=int(input())
C=(F-30)//2
print(C)

Python: F=int(input())
print(int((F-30)/2))

Python: a= int(input())
b=a-30
x=divmod(b,2)
print(x[0])

Python: F=int(input())
C=int((F-30)/2)
print(C)

Python: F = int(input())
print(int((F-30)/2))

Python: F=int(input())
C=(F-30)/2
print(int(C))

Python: f=int(input())
c=(f-30)//2
print(c)

Python: F = int(input())
print((F-30)//2)

Python: 
def solve():
    print(int((int(input()) - 30) / 2))


if __name__ == '__main__':
    solve()

Python: x=int(input())
print((x-30)//2)

Python: print((int(input())-30)//2)

Python: F=int(input())
print((F-30)//2)

Python: a = int(input())
print('{:.0f}'.format((a-30)/2))

Python: F=int(input())
C=(F-30)//2
print(C)

Python: a = int(input())
print(int((a-30)/2))

Python: a=int(input())
print(int(a-30)//2)

Python: x=int(input())
print(int((x-30)/2))

Python: F = int(input())
C = (F - 30) // 2
print(C)

Python: F = int(input())
C=(F-30)//2
print(C)

Python: F=int(input())
print((F-30)//2)

Python: f = int(input())

print( (f-30)//2 )

Python: F= int(input())
print((F-30)//2)

Python: f = int(input())
print(int((f - 30) / 2))

Python: F=int(input())
def C(F):
    C=(F-30)//2
    return C
print(C(F))

Python: F = int(input())
import math
print(math.floor((F-30)/2))

Python: F=int(input())
print((F-30)//2)

Python: kashi = int(input())
sesshi = int((kashi - 30)/2)
print(sesshi)

Python: x=int(input())
y=int((x-30)/2)
print(y)

Python: F = int(input())
print((F-30)//2)

Python: F = int(input())
print(int((F-30)/2))

Python: F = int(input())
print((F-30)/2)

Python: print((int(input())-30)//2)

Python: F=int(input())
print(int((F-30)/2))

Python: F=int(input())
print((F-30)//2)

Python: x=int(input())
print(int((x-30)/2))

Python: F = int(input())
print((F-30)//2)

Python: F=int(input())
C=(F-30)//2
print(C)

Python: # coding: utf-8
# Your code here!

F = int(input())
print((F-30)//2)

Python: f=int(input())
print((f-30)//2)

Python: F=int(input())
print(int((F-30)/2))

Python: F=int(input())
C=(F-30)//2
print(C)

Python: #! /usr/bin/env python
# -*- coding: utf-8 -*-
import sys
import math 

def main():
     f = int(input())
     c = int((f - 30) / 2)
     print(c)

if __name__ == '__main__':
    main()

Python: x=int(input())
print(round((x-30)/2))

Python: import math
F = int(input())
print(math.floor((F - 30)/2))

Python: F = int(input())
C = (F-30)/2
print(int(C))

Python: F = int(input())
print(int((F-30)/2))

Python: print(int((int(input())-30)/2))

Python: F = int(input())
print((F - 30) // 2)

Python: F = int(input())
C = int((F-30)/2)
print(C)

Python: def FtoC(F):
    C=(F-30)/2
    return C

F=int(input())
print(int(FtoC(F)))

Python: a = int(input())
print((a-30)//2)

Python: F=int(input());C=(F-30)/2;print(int(C))

Python: F=int(input())
C=(F-30)/2
print('{:0.0f}'.format(C))

Python: F=int(input())
print((int)((F-30)/2))

Python: F=int(input())
if F%2==0:
    C=(F-30)//2
    print(int(C))
else:
    pass

Python: f = int(input())
print((f-30)//2)

Python: F = int(input())
a = int((F - 30) / 2)
print(a)

Python: print(((int(input())) -30)//2)

Python: print((int(input())-30)//2)

Python: i=int(input())
print((i-30)//2)

Python: F=int(input())
C=(F-30)//2
print(C)

Python: F=int(input())
C=int((F-30)/2)
print(C)

Python: a = int(input())

print((a-30)//2)

Python: F = int(input())
C = int((F-30)/2)
print(C)

Python: f=int(input())
c=(f-30)//2
print(c)

Python: import math
f=int(input())
c=int((f-30)/2)
print(c)

Python: def F(f):
    return (f-30)//2

a=int(input())
print(F(a))

Python: x = input()
x = int(x)
y = (x-30)/2
print(int(y))

Python: import math
p=int(input())
c=(p-30)/2

print(math.floor(c))

Python: def fah(F):
    C=int((F-30)/2)
    return C
f=int(input())
print(fah(f))

Python: F = int(input())
print((F-30)//2)

Python: F=int(input())
print((F-30)//2)

Python: F=int(input())
print(int((F-30)/2))

Python: print(int(input())//2-15)

Python: F=int(input())
if 30<=F<=100:
   C=int((F-30)/2)
   print(C)
else:
   pass

Python: F=int(input())
print(int((F-30)/2))

Python: F=int(input())
print(int((F-30)/2))

Python: f=int(input())
c=(f-30)//2
print(c)

Python: # coding: utf-8
# Your code here!

F = int(input())
print(int((F - 30) / 2))

Python: F = int(input())
print((F-30)//2)

Python: # coding: utf-8
# Your code here!
F=int(input())

print(int((F-30)/2))

Python: F = int(input())
C = (F-30)/2
print('{:.0f}'.format(C))

Python: F=int(input())
C=(F-30)//2
print(C)

Python: F=int(input())
c=(F-30)//2
print(c)

Python: F=int(input())
C=(F-30)/2
print(int(C))

Python: x=int(input())
c=int((x-30)/2)
print(c)

Python: F = int(input())
print((F - 30) // 2)

Python: def to_cels(f):
    return (f-30)/2
while True:
    try:
        f=int(input())
        print(int(to_cels(f)))
    except:
        break

Python: 
F = int(input())
print((F - 30) // 2)

Python: x = int(input())
print((x-30)//2)

Python: a = int(input())
print(int((a-30)/2))

Python: F = int(input())
T = (F-30)//2
print(T)

Python: print((int(input())-30)/2)

Python: a=int(input())
print((a-30)//2)

Python: F=int(input())
print((F-30)//2)

Python: # coding: utf-8

print(int((int(input()) - 30) / 2))

Python: f = int(input())
print(int((f-30)/2))

Python: f=int(input())
print(f'{(f-30)/2:.0f}')

Python: F = int(input())
print((F-30)//2)

Python: a=int(input())
print(int((a-30)/2))

Python: f=int(input())
kotae=f-30
print(kotae//2)

Python: a=int(input())
print((a-30)//2)

Python: # coding: utf-8
# Your code here!
a = int(input())
print((a-30)//2) #小数点以下の桁数を0に指定

Python: x=int(input())

print(int((x-30)*1/2))

Python: F = int(input())
print(int((F-30)/2))

Python: print(int((int(input())-30)/2))

Python: F = int(input())
print ((F-30)//2)

Python: F = int(input())
print(int((F-30)/2))

Python: c=int(input())
x=c-30
print(int(x/2))

Python: n = int(input())

print((n-30)//2)

Python: F = int(input())
C = (F-30)/2
print(round(C))

Python: C = int(input())
F = (C-30)/2
print(int(F))

Python: F = int(input())
print((F - 30) // 2)

Python: F = int(input())

print((F - 30) // 2)

Python: x=int(input())
print(int((x-30)/2))

Python: F=int(input())
print((F-30)//2)

Python: F=int(input())
C=(F-30)/2
print(int(C))

Python: # coding: utf-8

F = int(input())
C = (F-30)/2
print(int(C))

Python: F = int(input())
C = ((F-30)//2)
print(C)

Python: F=int(input())
print((F-30)//2)

Python: f = int(input())
print((f - 30) // 2)

Python: F = int(input())
C = F - 30
C = int( F - 30)//2
print(C)

Python: F=int(input())
print((F-30)//2)

Python: print((int(input())-30)//2)

Python: F = int(input())
C = (F-30)//2
print(C)

Python: a=int(input())
print((a-30)//2)

Python: F=int(input())
print((F-30)//2)

Python: f = int(input())
print((f-30)//2)

Python: F=int(input())
print(int((F-30)/2))

Python: F = int(input())
print((F-30)//2)

Python: f=int(input())
print((f-30)//2)

Python: x=input()
x=int(x)
y=(x-30)//2
print(y)

Python: F = int(input())
C = (F-30)/2

print(int(C))

Python: F=int(input())
print(int((F-30)/2))

Python: print((int(input())-30)//2)

Python: print( (int(input())-30)//2 )

Python: x=int(input())
print(int((x-30)/2))