import os, sys, re, math

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

print(max(A - B * 2, 0)) import os, sys, re, math os sys re math int(n) for n in input().split() for n in input().split() n input().split() ().split () input split for n in input().split() int(n) int n (A, B) = [int(n) for n in input().split()] (A, B) A B [int(n) for n in input().split()] print(max(A - B * 2, 0)) print max(A - B * 2, 0) max A - B * 2 A B * 2 B 2 0
import os, sys, re, math

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

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