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-B*2))

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

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

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

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

b *= 2

if b>a:
    print(0)
else:
    print(abs(a-b))

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

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

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

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

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

Solution (Python):


import sys
input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**6)
INF = float("inf")

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


if __name__ == "__main__":
    main()

Solution (Python):



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



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

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

len_ = A-2*B

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

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

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

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

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

main()

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

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())

c = A-(2*B)

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

else:
    print(c)

Solution (Python):
a, b = 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)
elif A<=(B*2):
  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())

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

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

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

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

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

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

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

Solution (Python):
import sys




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

if __name__ == "__main__":
    main()

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

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

Solution (Python):

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

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

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

t = a-2*b

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

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

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

Solution (Python):
import sys

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

A,B = map(int,S().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())

if a > (b * 2):
    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):
import sys

read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10 ** 9)
INF = 1 << 60
MOD = 1000000007


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


if __name__ == '__main__':
    main()

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

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

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

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

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

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

ans=a-b*2

if ans>=0:
    print(ans)

else:
    print('0')

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

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-2*B))

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Solution (Python):
def curtain(x,y):
  if (2*b>=a):
    return 0;
  else:
    return (a-(2*b))
a,b=map(int,input().split())
print(curtain(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())
if b*2<a:
    print(a-b*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())
print(0 if (B * 2) >= A else A - (B * 2))

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

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

if __name__ == '__main__':
    main()

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

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

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

Solution (Python):
a1=input()
a2=[i for i in a1.split()]
a3,a4=[a2[i] for i in (0,1)]
A,B=int(a3),int(a4)
print(max(0,A-2*B))

Solution (Python):
import sys
sys.setrecursionlimit(4100000)
import math
INF = 10**9
import itertools

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

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

Solution (Python):
import math
import sys
from collections import deque
import heapq
import copy
import itertools
from itertools import permutations
def mi() : return map(int,sys.stdin.readline().split())
def ii() : return int(sys.stdin.readline().rstrip())
def i() : return sys.stdin.readline().rstrip()
a,b=mi()
print(max(a-b-b,0))

Solution (Python):

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

if __name__ ==  "__main__":
    main()

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

if __name__ == '__main__':
    solve()

Solution (Python):
import sys
a,b=map(int,input().split())
if a<=b*2:
  print('0')
  sys.exit()
print(a-b*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())
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())
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 2*b>=a:
    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 = input().split()
A = int(A)
B = int(B)
ans = max(0,A - 2*B)
print(ans)

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

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

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

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

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

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

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

result = a - b * 2

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

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

Solution (Python):

A, B = [int(s) for s in input().split()]
print(A - 2 * B if A - 2 * B > 0 else 0)

Solution (Python):
import os, sys, re, math

(A, B) = [int(n) for n in input().split()]

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

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

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

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

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

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())

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())

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

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

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

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


if __name__ == "__main__":
    main()

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

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

print(max(A - B * 2, 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(a-2*b,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())
if A - 2 * B > 0:
    print(A - 2 * B)
else:
    print(0)

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

Solution (Python):
from sys import stdin
a, b = map(int, stdin.readline().rstrip().split())

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

Solution (Python):

"""
A - Curtain
https://atcoder.jp/contests/abc143/tasks/abc143_a

"""
import sys


def solve(A, B):
    return max(0, A - B * 2)


def main(args):
    A, B = map(int, input().split())
    ans = solve(A, B)
    print(ans)


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

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-2*b))

Solution (Python):
import sys
from collections import defaultdict
readline = sys.stdin.buffer.readline



def geta(fn=lambda s: s.decode()):
    return map(fn, readline().split())


def gete(fn=lambda s: s.decode()):
    return fn(readline().rstrip())


def main():
    a, b = geta(int)

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


if __name__ == "__main__":
    main()

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

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

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

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

Solution (Python):
import sys

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


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


if __name__ == '__main__':
    solve()

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

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

Solution (Python):

import sys
import math
from bisect import bisect_left
from bisect import bisect_right
import collections
import copy
import heapq
from collections import defaultdict
from heapq import heappop, heappush
import itertools
input = sys.stdin.readline
from collections import defaultdict
from heapq import heappop, heappush

from decimal import *













































def inputInt(): return int(input())
def inputMap(): return map(int, input().split())
def inputList(): return list(map(int, input().split()))
def inputStr(): return input()[:-1]

inf = float('inf')
mod = 1000000007




def main():
	A,B = inputMap()

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






def bisect_left_reverse(a, x):
    if a[0] <= x:
        return 0
    if x < a[-1]:
        return len(a)
    
    ok = len(a) - 1
    ng = 0
    while (abs(ok - ng) > 1):
        mid = (ok + ng) // 2
        if a[mid] <= x:
            ok = mid
        else:
            ng = mid
    return ok

def bisect_right_reverse(a, x):
    if a[0] < x:
        return 0
    if x <= a[-1]:
        return len(a)
    
    ok = len(a) - 1
    ng = 0
    while (abs(ok - ng) > 1):
        mid = (ok + ng) // 2
        if a[mid] < x:
            ok = mid
        else:
            ng = mid
    return ok





def binary_search(list, item):
    low = 0
    high = len(list) - 1

    while low <= high:
        mid = (low + high) //2
        guess = list[mid]
        if guess == item:
            return mid
        if guess > item:
            high = mid -1
        else:
            low = mid + 1
    return None




def sunuke(N, K, mod=10**9+7):
	if N < K or K-1 < 0:
		return 0
	else:
		return combination(N-1, K-1, mod)




def combination(n, r, mod=10**9+7):
    r = min(r, n-r)
    res = 1
    for i in range(r):
        res = res * (n - i) * modinv(i+1, mod) % mod
    return res


def modinv(a, mod=10**9+7):
    return pow(a, mod-2, mod)

def egcd(a, b):
    if a == 0:
        return b, 0, 1
    else:
        g, y, x = egcd(b % a, a)
        return g, x - (b // a) * y, y




def H(n, r, mod=10**9+7):
	
	
    return combination(n+r-1, r, mod)


class Combination:
    """
    O(n)の前計算を1回行うことで，O(1)でnCr mod mを求められる
    n_max = 10**6のとき前処理は約950ms (PyPyなら約340ms, 10**7で約1800ms)
    使用例：
    comb = Combination(1000000)
    print(comb(5, 3))  
    """
    def __init__(self, n_max, mod=10**9+7):
        self.mod = mod
        self.modinv = self.make_modinv_list(n_max)
        self.fac, self.facinv = self.make_factorial_list(n_max)

    def __call__(self, n, r):
        return self.fac[n] * self.facinv[r] % self.mod * self.facinv[n-r] % self.mod

    def make_factorial_list(self, n):
        
        
        fac = [1]
        facinv = [1]
        for i in range(1, n+1):
            fac.append(fac[i-1] * i % self.mod)
            facinv.append(facinv[i-1] * self.modinv[i] % self.mod)
        return fac, facinv

    def make_modinv_list(self, n):
        
        modinv = [0] * (n+1)
        modinv[1] = 1
        for i in range(2, n+1):
            modinv[i] = self.mod - self.mod//i * modinv[self.mod%i] % self.mod
        return modinv



def dfs(graph,parent,counter,edge):
    stk = []
    stk.append(edge)
    while len(stk) > 0:
        p = stk.pop()
        for e in graph[p]:
            if parent[p] == e:
                continue
            else:
                parent[e] = p
                counter[e] += counter[p]
                stk.append(e)



if __name__ == "__main__":
	main()

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())

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

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

ans = a - (b*2)
if ans > 0:
    print(ans)
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(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-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())
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(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):
import sys
input = lambda : sys.stdin.readline().rstrip()

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-B))

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

Solution (Python):
import sys, re
from collections import deque, defaultdict, Counter
from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians
from itertools import accumulate, permutations, combinations, product
from operator import itemgetter, mul
from copy import deepcopy
from string import ascii_lowercase, ascii_uppercase, digits
from bisect import bisect, bisect_left
from fractions import gcd
from heapq import heappush, heappop
from functools import reduce
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()))
def ZIP(n): return zip(*(MAP() for _ in range(n)))
sys.setrecursionlimit(10 ** 9)
INF = float('inf')
mod = 10 ** 9 + 7

A, B = MAP()
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())
x = a - b * 2
if x > 0:
  print(x)
else:
  print(0)

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

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

Solution (Python):
import sys
import decimal 

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

def main():
    a, b = map(int, input().split())
    c = a - b*2
    if c < 0:
        print(0)
        return
    print(c)
            
    
    
main()

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

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())

ans = A - 2*B

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

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

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

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

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

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

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(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, raw_input().split(' '))
print max(0, a - (b << 1))

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

Solution (Python):
from collections import defaultdict, deque
import sys


def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def I(): return int(sys.stdin.buffer.readline())
def LS(): return sys.stdin.buffer.readline().rstrip().decode('utf-8').split()
def S(): return sys.stdin.buffer.readline().rstrip().decode('utf-8')
def IR(n): return [I() for i in range(n)]
def LIR(n): return [LI() for i in range(n)]
def SR(n): return [S() for i in range(n)]
def LSR(n): return [LS() for i in range(n)]
def SRL(n): return [list(S()) for i in range(n)]
def MSRL(n): return [[int(j) for j in list(S())] for i in range(n)]


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

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

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(0, 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())

N = A - 2 * B

if N > 0:
    print(str(N))
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):
a,b = list(map(int,input().split()))

a = a-b-b

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

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

Solution (Python):

import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


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


if __name__ == '__main__':
    main()

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

Solution (Python):
def curtain(a, b):

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

if __name__ == '__main__':
    main()

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

if A > b:
  print(A-b)
else:
  print(0)

Solution (Python):
from sys import stdin, setrecursionlimit


def main():
    input = stdin.buffer.readline
    a, b = map(int, input().split())
    ans = a - 2 * b
    if ans >= 0:
        print(ans)
    else:
        print(0)


if __name__ == "__main__":
    setrecursionlimit(10000)
    main()

Solution (Python):
from sys import stdin, setrecursionlimit


def main():
    input = stdin.buffer.readline
    a, b = map(int, input().split())
    if a - 2 * b >= 0:
        print(a - 2 * b)
    else:
        print(0)


if __name__ == "__main__":
    setrecursionlimit(10000)
    main()

Solution (Python):
from sys import stdin, setrecursionlimit


def main():
    input = stdin.buffer.readline
    a, b = map(int, input().split())
    print(max(0, a - 2 * b))


if __name__ == "__main__":
    setrecursionlimit(10000)
    main()

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

Solution (Python):
x = input().split()
a = int(x[0])
b = int(x[1])
c = a - b * 2
if c > 0:
  print(c)
else:
  print(0)

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

if N[1]*2 >= N[0]:
  print(0)
else:
  print(N[0]-N[1]*2)

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

Solution (Python):
def main():
    a, b = map(int, open(0).read().split())

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

if __name__ == '__main__':
    main()

Solution (Python):
import sys
sys.setrecursionlimit(10**6)

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())

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

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

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

Solution (Python):
a, b = map(int, input().rstrip().split())
b2 = b * 2
r = 0 if a <= b2 else a - b2
print(r)

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

Solution (Python):
a,b = list(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 = max(0, A-2*B)
print(ans)

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

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

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

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

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

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

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())

ans = a - min(a, 2 * b)
print(ans)

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

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))