Problem:
 Score : 100 points    Problem Statement The window of Takahashi's room has a width of A . There are two curtains hung over the window, each of which has a horizontal length of B . (Vertically, the curtains are long enough to cover the whole window.)  We will close the window so as to minimize the total horizontal length of the uncovered part of the window.
Find the total horizontal length of the uncovered parts of the window then.      Constraints  1 \leq A \leq 100  1 \leq B \leq 100  A and B are integers.         Input Input is given from Standard Input in the following format:  A  B       Output Print the total horizontal length of the uncovered parts of the window.        Sample Input 1 12 4      Sample Output 1 4  We have a window with a horizontal length of 12 , and two curtains, each of length 4 , that cover both ends of the window, for example. The uncovered part has a horizontal length of 4 .       Sample Input 2 20 15      Sample Output 2 0  If the window is completely covered, print 0 .       Sample Input 3 20 30      Sample Output 3 0  Each curtain may be longer than the window.

Solution (Python):
A, B = map(int, input().split())
print(max(0, A - 2 * B))

Solution (Python):
a,b = map(int,input().split())

if b*2 >= a:
    print(0)
else:
    print(a-b*2)

Solution (Python):
a, b = map(int, input().split())

if b * 2 >= a:
  print("0")
  
else:
  print(a - b*2)

Solution (Python):
A, B  = input().split()
B2 = int(B) * 2
ans = int(A) - B2
if ans < 0:
    ans = 0

print(ans)

Solution (Python):

import sys
sys.setrecursionlimit(300000)


def solve(A: int, B: int):
    ret = A - B * 2
    ret = max(ret, 0)
    print(ret)
    return

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

if __name__ == '__main__':
    main()

Solution (Python):
a, b = map(int, input().split())
print(max(0, a - 2 * b))

Solution (Python):
a,b = map(int ,raw_input().split())
print max(0,a-2*b)

Solution (Python):
A,B = map(int,input().split())

print(A-B*2 if A-B*2 >= 0 else 0)

Solution (Python):
A, B = map(int, input().split(' '))
print(max(0, A - 2*B))

Solution (Python):
A, B = map(int, input().split())
if A - 2 * B < 0 or A-2*B == 0:
    print(0)
else:
    print(A - 2 * B)

Solution (Python):
A, B = map(int, input().split())

if A >= 2 * B:
  print(A - 2 * B)
else:
  print(0)

Solution (Python):
a,b = map(int,input().split())
ans = a-2*b
if ans <= 0:
  print(0)
else:
  print(ans)

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

def main():
    A, B = map(int, input().split())
    print(max(0, A-2*B))

if __name__ == "__main__":
    main()

Solution (Python):
a, b = [int(x) for x in input().split()]
ans = a - 2*b

if(ans < 0):
		ans=0

print(ans)

Solution (Python):

def main():
    A,B = map(int,input().split())
    C = A-(B*2)
    if C < 0:
        C = 0
    print(C)

if __name__ == '__main__':
    main()

Solution (Python):


def main():
    A, B = map(int, input().split())
    Ans = max(A-B*2, 0)
    print(Ans)


if __name__ == "__main__":
    main()

Solution (Python):
A, B = map(int,input().split())
print(max(A - B * 2,0))

Solution (Python):
A, B = map(int, input().split())
print(max(A - 2 * B, 0))

Solution (Python):
a,b = map(int, input().split())
print(a-2*b if 2*b < a else 0)

Solution (Python):
a,b=map(int,input().split())
print(max(a-b*2,0))

Solution (Python):
a,b = (int(i) for i in input().split())
print(max(a-2*b,0))

Solution (Python):
A, B = map(int, input().split())
print(max(A-2*B,0))

Solution (Python):
A,B = [int(x) for x in input().split()]
print(max(0, A-2*B))

Solution (Python):
a,b = map(int,input().split())
if a-2*b>=0:
    print(a-2*b)
else:
    print(0)

Solution (Python):
a,b = map(int,input().split())

print(max(0,a-2*b))
'''
if b * 2 >= a:
    print(0)
else:
    print(a-2*b)
'''

Solution (Python):
from sys import stdin

window, curtain = [int(x) for x in stdin.readline().rstrip().split()]

if window < curtain*2:
  print(0)
else :
  print(window -curtain*2)

Solution (Python):
A, B = map(int, input().split())
r = max(0, A-2*B)
print(r)

Solution (Python):
A,B = [int(x) for x in input().split()]
if A - 2 * B <= 0:
    print(0)
else:
    print(A - 2 * B)

Solution (Python):
A, B = map(int, input().split())
print(A - B * 2 if A - B * 2 > 0 else 0)

Solution (Python):
a, b = map(int, input().split())

print(0 if a - (b * 2) < 0 else a - (b * 2))

Solution (Python):
a,b=map(int,input().split())
print(max(a-b*2,0))

Solution (Python):
a,b = map(int,input().split())
print(max(0,a-b*2))

Solution (Python):
A,B = map(int,input().split())
ANS = A - B * 2
if ANS <= 0:
  print(0)
else:
  print(ANS)

Solution (Python):
a, b = [int(x) for x in input().split()]
print(max(0, a - 2 * b))

Solution (Python):


def main():
    a, b = input().split()
    a, b = int(a), int(b)

    not_hidden = a - 2 * b
    print(max(0, not_hidden))

main()

Solution (Python):
a,b=map(int,input().split())
b=b*2
c=a-b
if c>=0 :
  ans=c
else :
  ans=0
  
print(ans)

Solution (Python):
a,b=map(int,input().split())
ans=a-2*b
if ans>0:
  print(ans)
else:
  print(0)

Solution (Python):
a,b=map(int,input().split())
c = a-b*2

print(0) if c < 0 else print(c)

Solution (Python):
A, B  =map(int,input().split())
if A-2*B >= 0:
    print(A-2*B)
else:
    print(0)

Solution (Python):
a, b = map(int, input().split())
print(max(0, a - 2*b))

Solution (Python):
import unittest
from io import StringIO
import sys


def input():
    return sys.stdin.readline().rstrip()


def resolve():
    A, B = map(int, input().split())
    ans = A-2*B
    if ans > 0:
        print(ans)
    else:
        print("0")


class TestClass(unittest.TestCase):
    def assertIO(self, input, output):
        stdout, stdin = sys.stdout, sys.stdin
        sys.stdout, sys.stdin = StringIO(), StringIO(input)
        resolve()
        sys.stdout.seek(0)
        out = sys.stdout.read()[:-1]
        sys.stdout, sys.stdin = stdout, stdin
        self.assertEqual(out, output)

    def test_入力例_1(self):
        input = """12 4"""
        output = """4"""
        self.assertIO(input, output)

    def test_入力例_2(self):
        input = """20 15"""
        output = """0"""
        self.assertIO(input, output)

    def test_入力例_3(self):
        input = """20 30"""
        output = """0"""
        self.assertIO(input, output)


if __name__ == "__main__":
    resolve()

Solution (Python):
a, b=map(int, input().split())
ans=a-2*b if a-2*b>0 else 0
print(ans)

Solution (Python):
A, B = map(int, input().split())

print(max(0, A - 2 * B))

Solution (Python):
A, B = map(int,input().split())
 
if(A > 2 * B):
  print(A - 2 * B)
else:
  print("0")

Solution (Python):
A, B = map(int, input().split())

if A < B * 2:
    C = 0
else:
	C = A - B * 2
	
print(C)

Solution (Python):
A, B=map(int, input().split())

if (A-2*B)>0:
  print(A-2*B)
else:
  print(0)

Solution (Python):
x,y = map(int,input().split())	
if x>2*y:
  print(x-2*y)
else:
  print(0)

Solution (Python):
a, b = map(int, input().split())

w = 0

if a<2*b :
    w = 0
    print(w)

else:
    w = a-2*b
    print(w)

Solution (Python):
a, b = [int(i) for i in input().split()]
print(max(0, a - 2 * b))

Solution (Python):
A, B = map(int, input().split())

print(max(A-B-B, 0))

Solution (Python):

a, b = map(int, input().split())
print(max(0, a - 2*b))

Solution (Python):
'''A - Curtain
https://atcoder.jp/contests/abc143/tasks/abc143_a

>>> main(12, 4)
4
>>> main(20, 15)
0
>>> main(20, 30)
0

'''


def main(a, b):
    print(max(0, a - b*2))


if __name__ == "__main__":
    a, b = map(int, input().split(' '))
    main(a, b)

Solution (Python):
A, B = map(int, input().split())
print(max(A-2*B, 0))

Solution (Python):
a,b = map(int, input().split())

print(max(0,a-2*b))

Solution (Python):
a,b = map(int,input().split())
s = a-b*2
if s <= 0:
    print(0)
else:
    print(s)

Solution (Python):
A, B = map(int, input().split())
print(max(A-B*2, 0))

Solution (Python):
A, B = map(int, input().split())

if 2 * B > A:
    print(0)
else:
    print(A - 2 * B)

Solution (Python):
a, b = map(int, input().split())
print(a - b * 2 if a >= b*2 else 0)

Solution (Python):
A, B = map(int, input().split())
print(max(0, A-2*B))

Solution (Python):
a,b = map(int, input().split())
print((a-(2*b)) if (a-(2*b))>0 else 0)

Solution (Python):
A,B=map(int,input().split())
C=A-2*B
if C<0:
    print(0)
else:
    print(C)

Solution (Python):
a, b  = map(int, input().split())
if a-b*2 >=0:
  print(a-b*2)
else:
  print(0)

Solution (Python):
A, B = map(int, input().split())

print(max(A-2*B, 0))

Solution (Python):
a, b = map(int, input().split())
print(max(a - b * 2, 0))

Solution (Python):
A,B=map(int,input().split())
print(A-2*B) if A>2*B else print(0)

Solution (Python):
a, b = map(int, input().split())



if (2 * b >= a):
  print(0)
  
else:
  print(a - 2 * b)

Solution (Python):
a,b=map(int,raw_input().split())
val = a-2*b
if val>0:
  print val
else:
  print 0

Solution (Python):
from heapq import heappush, heappop
from collections import deque,defaultdict,Counter
import itertools
from itertools import permutations,combinations
import sys
import bisect
import string



def I():
    return int(input())
def MI():
    return map(int,input().split())
def LI():
    return [int(i) for i in input().split()]
def LI_():
    return [int(i)-1 for i in input().split()]
def StoI():
    return [ord(i)-97 for i in input()]
def show(*inp,end='\n'):
    if show_flg:
        print(*inp,end=end)
YN=['Yes','No']
mo=10**9+7
inf=float('inf')



input=lambda: sys.stdin.readline().rstrip()

show_flg=False
show_flg=True

a,b=MI()
print(max(0,a-2*b))

Solution (Python):
a, b  = map(int, input().split())
print(max(0, a-2*b))

Solution (Python):


a,b=map(int,raw_input().split())
if a<2*b:
 print 0
else:
 print a-2*b

Solution (Python):
n, k = map(int, input().split())

k = k*2
ans = n - k
if ans < 0:
    print(0)
else:
    print(ans)

Solution (Python):
a,b=map(int,input().split())
ans=a-2*b
if ans<=0:
  print(0)
else:
  print(ans)

Solution (Python):
a, b = map(int, input().split())
print(a -2*b) if a-2*b > 0 else print(0)

Solution (Python):
a,b = map(int,input().split(" "))
if a <= b * 2:
  print(0)
else:
  print(a - b * 2)

Solution (Python):
a,b = (int(i) for i in input().split())
print(a-b*2 if a-b*2 >= 0 else 0)

Solution (Python):
a, b = map(int, input().split())
print(a - 2 * b if a > 2 * b else 0)

Solution (Python):
A, B = map(int, input().split())

if A > B*2:
  l = A - B*2
  print(l)
  
else:
  print('0')

Solution (Python):
a, b = map(int, input().split())
print(max(0, a - b * 2))

Solution (Python):
a, b = map(int, input().split())

if a - b * 2 >= 0:
  print(a - b * 2)
else:
  print(0)

Solution (Python):
a, b = map(int, input().split())
if a>(b*2): print(a-(b*2))
else: print(0)

Solution (Python):
A, B = map(int,input().split())
answer = A - (2 * B)
if answer >= 0:
    print(answer)
else:
    print(0)

Solution (Python):
a, b = map(int, input().split())
print(max(0, a - b * 2))

Solution (Python):
def solve():
    A, B = map(int, input().split())
    if A <= B * 2:
        print(0)
    else:
        print(A - B * 2)

if __name__ == '__main__':
    solve()

Solution (Python):
a,b=map(int,input().split())
print(max(a-b*2,0))

Solution (Python):
A, B = map(int, input().split())

print(max(0, A-2*B))

Solution (Python):
def main():
    a, b = map(int, input().split())
    c_length = b * 2
    ans = a - c_length
    if ans <= 0:
        print(0)
    else:
        print(ans)
        
main()

Solution (Python):
a,b = [int(x) for x in input().split()]
c = a - 2*b
if c < 0:
  c = 0
print(c)

Solution (Python):
if __name__ == "__main__":
    window,cartain=map(int,input().split())
    cartains=cartain*2
    if window-cartains<0:
        ans = 0
    else:
        ans = window-cartains
    print(ans)

Solution (Python):
A, B = map(int, input().split())
print(max(0, A - 2 * B))

Solution (Python):
a,b=map(int,input().split())
print(max(0,a-b*2))

Solution (Python):
a,b=map(int,input().split())
print(a-2*b if a > 2*b else 0)

Solution (Python):
a,b=map(int,input().split())
if a-2*b<0:
    print(0)
else:
    print(a-2*b)

Solution (Python):
a,b=map(int,input().split())
print(max([0,a-b-b]))

Solution (Python):
A, B = map(int, input().split())
C = int(A - B*2)

if C > 0 :
  print(C)
else :
  print(0)

Solution (Python):
a,b=(int(i) for i in input().split())
print(max((a-(2*b)),0))

Solution (Python):
a, b = map(int, input().split())

print(max(a - 2*b, 0))

Solution (Python):

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


c=a-2*b
print(max(c,0))

Solution (Python):
a,b =[int(i) for i in input().split()]
if  a-2*b>0:
    print(a-2*b)
else:
    print(0)

Solution (Python):

a, b = map(int, input().split())
ans = max(0, a-b*2)
print(ans)

Solution (Python):
A,B=map(int,input().split())
if 2*B<=A:
    print(A-2*B)
else:
    print(0)

Solution (Python):
num1,num2 = map(int,input().split())
if num1 >= 2*num2:
    print(num1 - 2*num2)
else:
    print('0')

Solution (Python):
A,B=map(int, input().split()) 
answer = A - 2*B
if answer < 0:
  answer = 0
 
print(answer)

Solution (Python):
n,m = map(int, input().split())
a = n - 2 * m

if a <= 0:
    print(0)
else:
    print(a)

Solution (Python):
A,B=map(int,input().split())
print(max(0,A-2*B))

Solution (Python):
A, B = map(int, input().split())
print(max(0, A - 2 * B))

Solution (Python):
A, B = map(int, input().split())
print(max(0, A - B * 2))

Solution (Python):
A, B = map(int, input().split())
print(max(0, A-B*2))

Solution (Python):
A, B = map(int, input().split())
N = A - 2*B
print (N if N >= 0 else 0)

Solution (Python):
a,b=map(int,input().split())
c=a-(b*2)
if c>0:
  print(c)
else:
  print(0)

Solution (Python):
A,B=map(int,input().split())
print(max(0,A-B*2))

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

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    a,b = LI()

    return max(0,a-b*2)


print(main())

Solution (Python):
def main():

    a, b = map(int, input().split())
    print(max(0, a-2*b))

if __name__ == '__main__':
    main()

Solution (Python):
A, B = map(int, input().split())
print(A - 2 * B if A > 2 * B else 0)

Solution (Python):
import sys

class Solution(object):
    def __init__(self):
        a = sys.stdin.readline().split()
        if len(a) != 2: return
        self.A = int(a[0])
        self.B = int(a[1])

    def get_open_window(self):
        if 2*self.B >= self.A:
            return 0
        return self.A - (2*self.B)

if __name__ == "__main__":
    s = Solution()
    print(s.get_open_window())

Solution (Python):
a,b = map(int,input().split())

if a < b * 2:
    print(0)
else:
    c = a - b * 2
    print(c)

Solution (Python):
a, b = map(int, input().split())
print(max(0, a - 2 * b))

Solution (Python):
a, b, = map(int, input().split())
print(max(a-2*b, 0))

Solution (Python):
a,b=map(int,input().split())
print(max(0,a-2*b))

Solution (Python):
A,B = map(int,input().split())
print(max(A-2*B,0))

Solution (Python):
import sys

[a, b] = map(int, input().split())
out = a - 2 * b if a - 2 * b > 0 else 0
print(out)

Solution (Python):
a, b = map(int, input().split())
if 2 * b >= a:
    print(0)
else:
    print(a - 2 * b)

Solution (Python):
a,b = (int(x) for x in input().split())
res = a - 2*b
if res < 0:
  res = 0
print(res)

Solution (Python):
a,b=map(int,input().split())
if(b*2>=a):
  print(0)
else:
  print(a-2*b)

Solution (Python):
a,b = (int(x) for x in input().split())
print(0 if a - b * 2 <= 0 else a - b * 2)

Solution (Python):
a,b=[int(s) for s in input().split()]
print(max([0,a-2*b]))

Solution (Python):
A,B=map(int,input().split())
c=A-2*B
print(max(0,c))

Solution (Python):
a,b = map(int,input().split())

print(a - b*2 if a-2*b >= 0 else 0)

Solution (Python):

def main():
    A, B = map(int, input().split())
    ans = max(0, A - 2 * B)
    print(ans)


if __name__ == "__main__":
    main()

Solution (Python):
A, B = [int(x) for x in input().split()]
print(max(0, A - B*2))

Solution (Python):
A,B = map(int,input().split())
print(max(0,A-B*2))

Solution (Python):
a,b = map(int,input().split())
print(max(a-b*2,0))

Solution (Python):

a, b = map(int, input().split(' '))
ans = a - 2 * b
if ans < 0:
	ans = 0
print(ans)

Solution (Python):
import sys
from collections import defaultdict, deque
from heapq import *
sys.setrecursionlimit(200000)
input = sys.stdin.readline

N, M, = map(int, input().split())







s = N - M * 2
if s < 0:
    print(0)
else:
    print(s)

Solution (Python):
a,b = map(int,input().split())
ans = a - 2*b
if ans < 0:
  ans = 0
print(ans)

Solution (Python):
A, B = map(int, input().split())
print(max(A - 2 * B, 0))

Solution (Python):
a, b = map(int, input().split())
print(max(0, a - (2*b)))

Solution (Python):
a,b = map(int,input().split())
print(max(0, a-(b*2)))

Solution (Python):
from sys import stdin
input = stdin.readline
lmi = lambda: list(map(int, input().split()))
mi = lambda: map(int, input().split())

a, b = mi()
print(max(0, a-(b*2)))

Solution (Python):
a, b = map(int, input().split())

if a > b*2:
    print(a - b*2)
else:
    print(0)

Solution (Python):
a,b=map(int,input().split())
print(max(a-2*b,0))

Solution (Python):
[a,b] = [int(i) for i in input().split()]
print(max(a-2*b,0))

Solution (Python):
print(max(0,eval(input().replace(' ','-2*'))))

Solution (Python):
print(max(0,eval(input().replace(' ','-2*'))))

Solution (Python):
a, b = map(int, input().split())

if a / 2 < b:
    print(0)
else:
    print(a - 2 * b)

Solution (Python):
A, B = map(int, input().split())
print(max(0, A - 2 * B))

Solution (Python):
A,B = map(int, input().split())

if A < 2 * B:
    print("0")
else:
    print(A - 2*B)

Solution (Python):
a, b = map(int, input().split())

if b * 2 >= a:
    print(0)
else:
    print(a - (b * 2))

Solution (Python):
wsize,csize=[int(x) for x in input().split()]
widthconsumed=csize*2
result=wsize-widthconsumed
if result>=0:
    print(result)
else:
    print(0)

Solution (Python):
a, b = map(int, input().split())
c = a - b * 2
if c >= 0:
  print(c)
else:
  print("0")

Solution (Python):
h , c = map(int , input().split())

res = 0
if h < c :
    print(res)
else:
    h-=2*c
    if h>=0 :
        res = h 
    print(res)

Solution (Python):
A, B = map(int, input().split())
ans = 0
tmp = A - (2 * B)

if 0 < tmp:
    ans = tmp
print(ans)

Solution (Python):
n = [int(e) for e in input().split(" ")]
ans = n[0] - (n[1] * 2)
print(ans if 0 < ans else 0)

Solution (Python):
a, b = list(map(int, input().split()))

if b > a:
  print("0")
elif b*2 > a:
  print("0")
else:
  anser = a - (b*2)
  print(anser)

Solution (Python):
a,b=map(int,input().split())
if a-b*2<=0:
  
  print(0)
else:
  print(a-b*2)

Solution (Python):
a,b=map(int,input().split())
if (b*2)<=a:
  print(a-(b*2))
else:
  print("0")

Solution (Python):
A, B = map(int, input().split())

print(max(A - 2*B, 0))

Solution (Python):
A,B=map(int,input().split())

print(max(0,A-2*B))

Solution (Python):
temp = input().split()
an = int(temp[0])-2*int(temp[1])
if an <= 0:
  print(0)
else:
  print(an)

Solution (Python):
A,B = map(int, input().split())
if A-2*B <= 0:
    print(0)
else:
    print(A-2*B)

Solution (Python):
a,b = map(int, input().split())
print(max(0, a-2*b))

Solution (Python):
length = [int(i) for i in input().split()]
if length[0] >= length[1]*2:
  print(length[0]-length[1]*2)
else:
  print(0)

Solution (Python):
a,b = map(int,input().split())

print(max(0, a-2*b))

Solution (Python):
A,B = map(int, input().split())


if A - 2*B > 0:
    print(A - 2*B)
else:
    print(0)

Solution (Python):
A, B = map(int, input().split())
print(max(0, A - 2 * B))

Solution (Python):
a, b = map(int, input().split())
print(a - 2 * b if a > 2 * b else 0)

Solution (Python):
a, b = map(int, input().split())
print(max(a - b * 2, 0))

Solution (Python):
A, B = map(int, input().split())
print(max(0, A - 2*B))

Solution (Python):
import copy

def j(n):
    if n:print("yes")
    else:print("no")
    exit(0)
rem = 10 ** 9 + 7

"""
def ct(x,y):
    if (x>y):print("+")
    elif (x<y): print("-")
    else: print("?")
"""

def ip():
    return int(input())
def iprow():
    return [int(i) for i in input().split()]
def ips():
    return (int(i) for i in input().split())
def ipmultiplerow(n):
    a = []
    for i in range(n):
        a.append(ip())
    return a
def printrow(a):
    for i in a:
        print(i)

a,b = ips()

print(max(0,a-2*b))

Solution (Python):
s=list(map(int,input().split()))
if 2*s[1]>=s[0]:
  print(0)
else:
  print(s[0]-2*s[1])

Solution (Python):
a, b = map(int, input().split())
if a-2*b >= 0:
    print(a-2*b)
else:
    print(0)

Solution (Python):
a,b=map(int,input().split())
print(0 if a<=(2*b) else a-(2*b))

Solution (Python):
A, B = map(int, input().split())

print(max(A-2*B, 0))

Solution (Python):
A, B = map(int, input().split())
print(max(0, A - 2 * B))

Solution (Python):
a,b=map(int,input().split())

if a-2*b>0:
    print(a-2*b)
else:
    print(0)

Solution (Python):
[a,b] = map(int, input().split(" "))
L = a - 2 * b
if L < 0:
  L = 0
print(L)

Solution (Python):
a,b = map(int,input().split())
print(max(0,a-2 * b))

Solution (Python):
A,B = map(int, input().split())
ans = A - B * 2
if ans < 0:
  ans = 0
print(ans)

Solution (Python):



a, b = map(int, input().split())
sum = a-2*b
if sum > 0:
    print(sum)
else:
    print(0)

Solution (Python):
a,b = map(int,input().split())
c = a - 2 * b
if c < 0:
  print(0)
  exit()
print(c)

Solution (Python):
A,B = map(int,input().split())
length = A-2*B
if length<=0:
  print(0)
else:
  print(length)

Solution (Python):
a,b=map(int,input().split())
print(max(a-b*2,0))

Solution (Python):
a, b = map(int, input().split())
if a - b * 2 >= 0:
    print(a - b * 2)
else:
    print(0)

Solution (Python):

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

result = a - 2 * b

if result <= 0:
    print(0)
else:
    print(result)

Solution (Python):
a, b = input().split()
a = int(a)
b = int(b)

if a >= 2 * b:
  print(a - 2 * b)
  
else:
  print(0)

Solution (Python):
a, b= map(int, input().split())

c=a-b*2

if c<=0:
    print(0)
else:
    print(c)

Solution (Python):
A, B = map(int, input().split())
ans = A - B - B
if ans > 0:
  print(ans)
else:
  print(0)

Solution (Python):
a,b = map(int,input().split())
ans = a- 2*b

if ans < 0:
  ans = 0

print(ans)

Solution (Python):
A,B=list(map(int,input().split()))
if A-B*2 < 0:
  print(0)
else:
  print(A-B*2)

Solution (Python):
a,b = map(int, input().split())
print(max(0,a-2*b))

Solution (Python):
A,B = map(int,input().split())
print(max(A-2*B,0))

Solution (Python):
A, B = list(map(int, input().split()))

print(max(0, A - 2 * B))

Solution (Python):
A,B=map(int,input().split())

if A>B*2:
  print(A-B*2)

else:
  print(0)

Solution (Python):
A,B=raw_input().split()

a = int(A)
b = int(B)

c = a - 2 * b

print 0 if c < 0 else c

Solution (Python):
A,B=map(int,input().split())
if A-B*2>0:
    print(A-B*2)
else :
    print('0')

Solution (Python):
all=list(map(int,input().split()))

print(max(0,all[0]-all[1]*2))

Solution (Python):
A, B = map(int, input().split())
print(max(0, A-2*B))

Solution (Python):
a, b = map(int, input().split())
print(max(0, a - 2 * b))

Solution (Python):
A, B = map(int, input().split())
print(A-2*B) if A > 2*B else print(0)

Solution (Python):
a,b=map(int,input().split())

rest=a-b*2
if rest<=0:
  print(0)
else:
  print(rest)

Solution (Python):
a, b = input().split()
A = int(a)
B = int(b)
C =A-B*2
if C > 0:
  	print(C)
else :
  print(0)

Solution (Python):
a,b = map(int, input().split())

ans = a - b*2

if ans < 0:
	ans = 0
print(ans)

Solution (Python):
a,b = map(int,input().split())
c=a-b*2

if c>=0:
    print(c)
elif c<0:
    print(0)

Solution (Python):
a,b = map(int, input().split())
print(max(0,a-2*b))

Solution (Python):
n,m=(map(int,input().split()))
if n<=2*m:
    print(0)
else:
    print(n-2*m)

Solution (Python):
def main():
 A, B = map(int, input().split())
 print(A-2*B) if A > 2*B else print(0)
  
main()

Solution (Python):
A,B=map(int,input().split())
print(max(0,A-2*B))

Solution (Python):
import sys

input = sys.stdin.readline

if __name__ == '__main__':
    A, B = map(int, input().split())

    print(max(0, A - B * 2))

Solution (Python):
a, b = map(int, input().split())
print(max(0, a-2*b))

Solution (Python):
a,b=list(map(int,input().split()))
s=a-2*b
if s<=0:
    print(0)
else:
    print(s)

Solution (Python):
a, b = map(int, input().rstrip().split())

if a < 2 * b:
  print(0)
else:
  print(a - 2 * b)

Solution (Python):
i = input()
a = int(i.split(' ')[0])
b = int(i.split(' ')[1])

if a - 2*b>=0:
  print(a - 2*b)
else:
  print(0)

Solution (Python):
a,b =map(int, input().split())
if a-2*b>0:
    print(a-2*b)
else:
    print(0)

Solution (Python):
N=list(map(int,input().split()))
if N[0]-N[1]*2>0:
  print(N[0]-N[1]*2)
else:
  print(0)

Solution (Python):
"""
author : halo2halo
date : 19,Oct,2019
"""

import sys
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10 ** 7)

A, B = map(int, readline().split())
print(max(A-2*B, 0))

Solution (Python):
values = list(map(int, input().split()))
a = values[0]
b = values[1]

sub = (a - 2*b)
if sub < 0:
    sub = 0

print(sub)

Solution (Python):
A,B=map(int,input().split())
m=A-2*B
if m<0:
  print(0)
else:
  print(m)

Solution (Python):
A,B = list(map(int,input().split()))
ans = 0
if A-B*2 > 0 :
    ans = A-B*2
else:
    ans = 0

print(ans)

Solution (Python):
A, B = map(int, input().split())
A -= B*2
if A<0:
    A = 0
    print(A)
else:
    print(A)

Solution (Python):
A, B = map(int, input().split(" "))

ans = 0
ans = A - 2 * B
if ans < 0:
  ans = 0
print(ans)

Solution (Python):
A,B = list(map(int,input().split()))

if A - 2*B > 0:
    print(A - 2*B)
else:
    print(0)

Solution (Python):
a, b = map(int, input().split())
print(max(a - b * 2, 0))

Solution (Python):
a, b = list(map(int, input(). split())) 
if 2*b > a :
  print (0) 
else:
  print (a-2*b)

Solution (Python):
A, B = list(map(int, input().split()))



if A - B*2 >= 0:
    print(A - B*2)
else:
    print(0)

Solution (Python):
a,b=[int(i) for i in input().split()]
print(max(a-b*2,0))

Solution (Python):
AB = input().split()
A = int(AB[0])
B = int(AB[1])
if A >= 2*B:
    print(A-(2*B))
else:
    print("0")

Solution (Python):
tmp = list(map(int, input().split()))
a = tmp[0]
b = tmp[1]

l = a - b * 2
if l < 0:
  l = 0
print (l)

Solution (Python):
a,b = map(int,input().split())

ans = max(0, a-2*b)

print(ans)

Solution (Python):
a,b=map(int,input().split())
if a<2*b:
    print(0)
else:
    print(a-(2*b))

Solution (Python):
a, b = [int(i) for i in input().split()]
n = a-b*2
print(0 if n<0 else n)

Solution (Python):
A,B=map(int,input().split())
if A < 2*B :
 print(0);
else:
  print(A-2*B)

Solution (Python):


A, B = map(int, input().split())
x = A - B * 2
print(x if x >= 0 else 0)

Solution (Python):
input_number = [int(n) for n in input().split()]
ret = input_number[0]-(input_number[1]*2)
if ret < 0:
    print("0")
else:
    print(ret)

Solution (Python):
A, B = map(int, input().split())

ans = 0
if B*2 >= A:
    ans = 0
else:
    ans = A - B*2

print(ans)

Solution (Python):
import sys
sys.setrecursionlimit(int(1e6))

A, B = list(map(int, input().split()))

ans = A - 2 * B;
print(max(ans, 0))

Solution (Python):
(A,B) = (int(n) for n in input().split())
short = A - 2*B
print(short if short>=0 else 0)

Solution (Python):
num =input()
lst = num.split()
curtain = int(lst[1]) * 2
ans = int(lst[0]) - curtain

if(ans <= 0):
 print("0")
else:
 print("{}".format(ans))

Solution (Python):


A, B = map(int, input().split())

gap = A - B * 2

if gap <= 0:
    print(0)
else:
    print(gap)

Solution (Python):
a,b=input().split()
a=int(a)
b=int(b)
c=a-2*b
if c<=0:
    print(0)
else:
    print(c)

Solution (Python):
A,B = map(int,input().split())
print(A-B*2 if A > B*2 else 0)

Solution (Python):
a, b = map(int, input().split())
print(max(0, a - b * 2))

Solution (Python):
A, B = map(int, input().split())

diff = A - 2 * B

if(diff > 0):
  print(diff)
else:
  print("0")

Solution (Python):
a,b = map(int,input().split())
if(a<=2*b):
  print(0)
else:
  print(a-2*b)

Solution (Python):
input_line = input()
a, b = [int(item) for item in input_line.split(' ')]
if a < b * 2:
    print(0)
else:
    print(a - b * 2)

Solution (Python):
A,B = [int(x) for x in input().split()]
ans = max(0,A-2*B)
print(ans)

Solution (Python):
import sys
from collections import Counter, deque, defaultdict
from math import factorial
import heapq, bisect
import math
import itertools
sys.setrecursionlimit(10 ** 5 + 10)
INF = 10**15 +5
def input(): return sys.stdin.readline().strip()
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(): return list(map(int, input().split()))

a, b = MAP()
b *= 2
print(max(a-b,0))

Solution (Python):
A, B = (int(i) for i in input().split())

if A - 2*B < 0:
    print(0)
else:
    print(A-2*B)

Solution (Python):
a, b = map(int, input().split())
s = a - b * 2
print(0 if s < 0 else s)

Solution (Python):
A, B = map(int, input().split())
 
value = A - B * 2
if value >= 0:
  print(value)
else:
  print(0)

Solution (Python):
a, b = map(int, input().split())
ans = a - b * 2

if ans <= 0:
    print(0)
else:
    print(ans)

Solution (Python):
x,y = map(int,input().split())
ans = x - y * 2
if(ans < 0):
    print(0)
else:
    print(ans)

Solution (Python):
s = list(input().split())
print(max(0,int(s[0]) - (int(s[1]) * 2)))

Solution (Python):
A, B = map(int, input().split())

print(A - 2 * B if (A - 2 * B) > 0 else 0)

Solution (Python):
a,b = map(int,input().split())
b = b*2
if a <= b:
  print(0)
else:
  print(a-b)

Solution (Python):
a, b= map(int, input().split())
if a<=2*b:
	print('0')
else:
	print(a-2*b)

Solution (Python):
A, B = map(int, input().split())
C = 2*B
ans = A-C
if ans < 0:
    ans = 0
print(ans)

Solution (Python):
n,m=map(int,input().split())
print(max(0,n-(2*m)))

Solution (Python):
data = input()
print(max(int(data.split(' ')[0])-int(data.split(' ')[1])*2,0))

Solution (Python):
A, B = [int(i) for i in input().split()]


l = A - 2*B
if l <= 0:
    l = 0
print(l)

Solution (Python):
import sys
a, b = map(int, input().split())
bb = b * 2

if a < b:
	print(0)
elif a >= b and a < bb:
	print(0)
else:
	print(a - bb)

Solution (Python):

a, b = (int(i) for i in input().split())

if (a > 2*b):
    print(a - 2*b)
else:
    print(0)

Solution (Python):
A,B=map(int,input().split())
math=A-(B*2)
if math<0:
    math=0
print(math)

Solution (Python):
A,B=map(int,input().split())
if A-2*B>0:
  print(A-2*B)
else:
  print(0)

Solution (Python):
A,B=map(int,input().split())
s=A-2*B
if s<0:
  print(0)
else:
  print(s)

Solution (Python):
A,B = map(int,input().split())

print(max(A-2*B,0))

Solution (Python):
ABInput = str(input())
 
AB = ABInput.split(" ")
 
A = int(AB[0])
B = int(AB[1])
 
TotalCartain = B * 2
 
if TotalCartain > A or TotalCartain == A:
  print (0)
else:
  print (A-TotalCartain)

Solution (Python):
a, b = (int(i) for i in input().split())
print(max(0, a - b*2))