import re
from sys import stderr
from typing import Union, Generator, List, Tuple
import string


EPS = 1e-10


def main():
    rc, xc, yc, x, y = map(int, input().split())

    distance = ((x - xc) ** 2 + (y - yc) ** 2) ** 0.5
    rc *= 2
    if distance % rc < EPS:
        res = distance // rc
    else:
        res = distance // rc + 1

    print(int(res))


if __name__ == '__main__':
    main()
