import sys
from math import sqrt, pi, sin, factorial
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = " " : [*map(int,inp().split(x))]
mfi = lambda x = " " : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
rng = range
def solve():
n = ii()
ans = 0
for i in range(n // 4 + 1):
y = n - i * 4
if y % 5:
continue
ans += 1
print(ans)
if __name__ == "__main__":
tc = 1
for t in rng(tc):
solve()