Count the number of prime numbers less than a non-negative number, n.

Example:


Input: 10
Output: 4
Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7.

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

def _disabled_input(*args, **kwargs):
    raise RuntimeError("input() is disabled in callable mode")
builtins.input = _disabled_input

ns = {"__name__": "__judge__"}  # prevent if __name__ == "__main__" blocks
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = 'class Solution:\n     def countPrimes(self, x):\n         x = max(0, x - 1)\n         if type(x) is not int: x = int(x)\n         if x < 6: return [0, 0, 1, 2, 2, 3][x]\n     \n         def Phi(m, b):\n             if not b:\n                 return m\n             if not m:\n                 return 0\n             if m >= 800:\n                 return Phi(m, b - 1) - Phi(m // primes[b - 1], b - 1)\n             t = b * 800 + m\n             if not Phi_memo[t]:\n                 Phi_memo[t] = Phi(m, b - 1) - Phi(m // primes[b - 1], b - 1)\n             return Phi_memo[t]\n         \n         \n         root2 = int(x**(1. / 2))\n         root3 = int(x**(1. / 3))\n         top = x // root3 + 1\n         sieve = [0, 0] + [1] * (top - 2)\n         pi = [0, 0]\n         primes = []\n         t = 0\n         for i in range(2, top):\n             if sieve[i] == 1:\n                 t += 1\n                 primes.append(i)\n                 sieve[i::i] = [0] * len(sieve[i::i])\n             pi.append(t)\n         a, b = pi[root3 + 1], pi[root2 + 1]\n         Phi_memo = [0] * ((a + 1) * 800)\n         return Phi(x, a) + a - 1 - sum(pi[x // p] - pi[p] + 1 for p in primes[a:b])'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'countPrimes'
if _fn_name:
    if "Solution" in ns:
        try:
            _obj = ns["Solution"]()
            if hasattr(_obj, _fn_name):
                _target = getattr(_obj, _fn_name)
        except Exception:
            _target = None
    if _target is None and _fn_name in ns and callable(ns[_fn_name]):
        _target = ns[_fn_name]
# Fallback: if there's exactly one user-defined function, use it
if _target is None:
    _cands = [v for k, v in ns.items() if callable(v) and getattr(v, "__module__", "") in ("__judge__", "__main__")]
    _user_funcs = [c for c in _cands if getattr(c, "__name__", "").startswith("_") is False]
    if len(_user_funcs) == 1:
        _target = _user_funcs[0]
if _target is None:
    raise RuntimeError(f"Could not resolve callable '{_fn_name}'")

_raw = sys.stdin.read().strip()
if _raw:
    _parsed = json.loads(_raw)
    if isinstance(_parsed, dict):
        _kwargs = _parsed.get("kwargs", {})
        _args = _parsed.get("args", [])
    else:
        _args, _kwargs = _parsed, {}
else:
    _args, _kwargs = [], {}
if not isinstance(_args, (list, tuple)):
    _args = [_args]
_res = _target(*_args, **_kwargs)
try:
    sys.stdout.write(repr(_res) + "\n")
except Exception:
    pass

```

Measured memory_bytes: 26542