import math



while True:

    try:

        v = eval(input())

        t = v/9.8

        y = v/2*t

        n = math.ceil(y/5.0)+1

        print(int(n))

    except:

        break
import math,sys

for e in sys.stdin:

    v=float(e[:-1])

    t=v/9.8

    y=v/2*t

    n=int(math.ceil(y/5))+1

    print(n)
import math

while True:
    try:
        v = eval(input())
        t = v / 9.8
        y = v / 2 * t
        n = math.ceil(y / 5.0) + 1
        print(int(n))
    except:
        break

import math, sys

for e in sys.stdin:
    v = float(e[:-1])
    t = v / 9.8
    y = v / 2 * t
    n = int(math.ceil(y / 5)) + 1
    print(n)

-import math +import math, sys -while True: -    try: -        v = eval(input()) -        t = v / 9.8 -        y = v / 2 * t -        n = math.ceil(y / 5.0) + 1 -        print(int(n)) -    except: -        break +for e in sys.stdin: +    v = float(e[:-1]) +    t = v / 9.8 +    y = v / 2 * t +    n = int(math.ceil(y / 5)) + 1 +    print(n)