import math
a = []
b = []
x = int(input())
while x != 0:
     a.append(x)
     x = int(input())
l = len(a)


for i in range(0,l):
     num = 0
     for j in range(1,a[i]+1):
          f = True
          for k in range(2,int(math.sqrt(j))+1):
               if j % k == 0:
                    f = False
                    break
          if j != 1 and f == True:
               num += 1
     b.append(num)

for l in b:
     print(l)
/**************************************************************
	Problem: 1176
	User: admin
	Language: Python
	Result: Accepted
	Time:113 ms
	Memory:34480 kb
****************************************************************/