import sys
import math
import bisect


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

if __name__ == "__main__":
    main() import sys sys import math math import bisect bisect def main():
    n, m = map(int, input().split())
    n = max(0, n - 2 * m)
    print(n) main n, m = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split m n = max(0, n - 2 * m) n max(0, n - 2 * m) max 0 n - 2 * m n 2 * m 2 m print(n) print n if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def main():
    n, m = map(int, input().split())
    n = max(0, n - 2 * m)
    print(n) def main():
    n, m = map(int, input().split())
    n = max(0, n - 2 * m)
    print(n) main
import sys
import math
import bisect


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

if __name__ == "__main__":
    main()
