import sys





def input():

    return sys.stdin.readline().rstrip()





def main():

    X =int(eval(input()))

    if X<30:

        print("No")

    else:

        print("Yes")





    pass





if __name__ == "__main__":

    main()

x=int(eval(input()))

if x >=30:

  print("Yes")

else:

  print("No")
import sys


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


def main():
    X = int(eval(input()))
    if X < 30:
        print("No")
    else:
        print("Yes")
    pass


if __name__ == "__main__":
    main()

x = int(eval(input()))
if x >= 30:
    print("Yes")
else:
    print("No")

-import sys - - -def input(): -    return sys.stdin.readline().rstrip() - - -def main(): -    X = int(eval(input())) -    if X < 30: -        print("No") -    else: -        print("Yes") -    pass - - -if __name__ == "__main__": -    main() +x = int(eval(input())) +if x >= 30: +    print("Yes") +else: +    print("No")