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