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

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

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

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

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

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

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

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

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

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

Solution (Python):
length, curtain = map(int, input().split())

res = length - (curtain * 2)

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

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

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

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

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

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

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

Solution (Python):

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

s = int()

if A <= 2 * B:
    s = 0
else:
    s = A - 2 * B

print(s)

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

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

Solution (Python):
str = input().split() 
a = int(str[0])
b = int(str[1])
ans = a - 2*b
if ans < 0:
    ans = 0
print(ans)

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

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

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

Solution (Python):

if __name__ == '__main__':

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

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

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

Solution (Python):
import sys
import math

N,K=map(int,input().split())
print(max(N-K*2,0))

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

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

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

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

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

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

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

ans = A - (B*2)

if ans < 0:
  ans = 0

print(ans)

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

Solution (Python):
a, b = list(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(A - 2*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())

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

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

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

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

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

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

Solution (Python):


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


if __name__ == "__main__":
    main()

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

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

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

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

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

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

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

Solution (Python):
def print_ans(input_line):
    """Test Case
    >>> print_ans("12 4")
    4
    """
    A, B = list(map(int,input_line.split()))
    print(str(max(0,A - B * 2)))

if __name__ == '__main__':
    input_line = input()
    print_ans(input_line)

Solution (Python):


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

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

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

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

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

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

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

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

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

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

Solution (Python):

a, b = list(map(int, input().split()))
result = a - (2 * b)

if result >= 0:
    print(result)
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, input().split())
print(max(A - 2 * B, 0))

Solution (Python):
aa, bb =input().split()
if int(aa)-2*int(bb)>0:
  print(int(aa)-2*int(bb))
else:
  print(0)

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

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

Solution (Python):
A,B = map(int,input().split())
print(max(A-(2*B),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=[int(_) for _ in input().split()]
print([a-2*b,0][0>a-2*b])

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

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

C = int(A) - int(B) * 2

if C < 0:
    print(0)
elif C > 100:
    print(100)
else:
    print(C)

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

C = int(A) - int(B) * 2

if C < 0:
    print(0)
elif C > 100:
    print(100)
else:
    print(int(C))

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

C = int(A) - int(B) * 2

if C < 1:
    print(0)
elif C > 100:
    print(100)
else:
    print(C)

Solution (Python):
A,B = map(int,input().split())
if A - B*2 >= 1:
  print(A - B*2)
else:
  print(0)

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

ans = a - 2*b
if (ans > 0):
  print(ans)
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 = list(map(lambda x: int(x.strip()), input().split()))

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

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

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-2*b, 0))

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

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

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

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 A>2*B else 0)

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

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

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

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

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

Solution (Python):



stu_bangou = list(map(int, input().strip().split()))

if stu_bangou[0] < (stu_bangou[1] * 2):
    print(0)
else:
    print(stu_bangou[0] - (stu_bangou[1] * 2))

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


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

if __name__ == "__main__":
    solve()

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

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

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, raw_input().split())
print max(0, A-B*2)

Solution (Python):
import math

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

answer=0

if A-2*B<=0:
    answer=0
else :
    answer=A-2*B

print(answer)

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

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

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

Solution (Python):


MOD = 10 ** 9 + 7

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

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

print(ans)

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())

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

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

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

if __name__ == '__main__':
    main()

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

Solution (Python):
import numpy as np
A, B = map(int, input().split())

res = A - 2*B
if res >= 0:
	print(res)
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())
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(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
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

print(x)

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

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())
X = a-(b*2)

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

Solution (Python):
A,B = [int(i) for i in 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 > 0:
    print(A-B*2)
else:
    print(0)

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

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

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

Solution (Python):

def curtain():
    inStr = input().split()
    a = int(inStr[0])
    b = int(inStr[1])
    
    ans = a - b * 2
    if (ans <= 0):
        print(0)
    else:
        print(ans)
curtain()

Solution (Python):

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

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

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

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

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

Solution (Python):
from sys import stdin
a, b = [int(x) for x in stdin.readline().rstrip().split()]
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())

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

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

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

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

ans = 0

if a - b*2 > 0:
    ans = a - b*2

print(ans)

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

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

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

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

ans=a-2*b

if ans<0:
    ans=0

print(ans)

Solution (Python):
"""
カーテンが2枚、縦は無視していいというのをすぐ把握すること。
カーテンの長さの合計が窓の長さを上回った時0になる。
制約
A,Bは整数
1≦A≦100
1≦B≦100
"""

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

Solution (Python):
print(max(0, sum([i*j for i, j in zip(map(int, input().split()), [1, -2])])))

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

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

Solution (Python):

import sys
sys.setrecursionlimit(12345678)
import itertools
from collections import Counter
from collections import defaultdict
from collections import deque
import bisect
from heapq import heappush, heappop


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

if __name__ == '__main__':
    main()

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

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

c = a - b * 2

if c < 0:
    c = 0

print(c)

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

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

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

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

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

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

Solution (Python):
a = input().split(" ")
a, b = int(a[0]), int(a[1]) * 2
r = a - b
print(r) if r > 0 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())

ans = A - (2*B)

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

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

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

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

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

c = a - 2 * b

if(c>0):
    print(c)
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):
x = list(map(int,input().split()))
if(x[0]-2*x[1]<=0):
    print(0)
else:
    print(x[0]-2*x[1])

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

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

ans = A - B * 2

print(0 if ans < 0 else ans)

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

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

Solution (Python):
s = list(map(int, input().split()))
A = s[0] 
B = s[1]
result = A - B * 2
if result < 0:
    result = 0
print(result)

Solution (Python):
import sys
sys.setrecursionlimit(1000000000)
ii = lambda: int(input())
mis = lambda: map(int,input().split())
lmis = lambda: list(mis())
INF = float('inf')

def main():
    A,B=mis()
    print(max(A-B*2,0))


if __name__ == "__main__":
    main()

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

Solution (Python):

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

c = a-(b*2)

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

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

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

Solution (Python):
import sys
sys.setrecursionlimit(10000000)
def input():
    return sys.stdin.readline()[:-1]
from bisect import *
from collections import *
from heapq import *
import itertools
import math
INF = 10**9
MOD = 10**9+7

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):
words = lambda t : list(map(t, input().split()))
a,b = words(int)

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

Solution (Python):
import sys


def solve():
    input = sys.stdin.readline
    mod = 10 ** 9 + 7
    a, b = list(map(int, input().rstrip('\n').split()))
    print(max(0, a - b * 2))


if __name__ == '__main__':
    solve()

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

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

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

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

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

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

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

Solution (Python):
A_B = input().split(' ')
A = int(A_B[0])
B = int(A_B[1])

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

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

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

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

S=A-2*B

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

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

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

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

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

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

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

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

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

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

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

Solution (Python):




import sys

readline = sys.stdin.readline 

a,b = [int(i) for i in readline().split()]

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

Solution (Python):
a= input().split(" ")

a1=int(a[0])
a2=int(a[1])

res = a1 - 2 * a2

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

Solution (Python):


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

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

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

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

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

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

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

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

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

Solution (Python):
nums = [int(e) for e in input().split()]

if nums[0]>100 or nums[1]>100:
  print('入力値が違います')
elif nums[0]<1 or nums[1]<1:
  print('入力値が違います')
elif nums[0]>2*nums[1]:
  print(nums[0]-2*nums[1])
else:
  print(0)

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

Solution (Python):
import sys

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

if window > width * 2:
    print(window - width * 2)
else:
    print(0)

Solution (Python):
A,B = map(int, open(0).read().split())

H=A-2*B

if H<0:
    H=0

print(H)

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

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

Solution (Python):
num1,num2=input().split()

a=int(num1)
b=int(num2)

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

elif a>b:
  c=a-2*b
  print(c)