In a 1 million by 1 million grid, the coordinates of each grid square are (x, y) with 0 <= x, y < 10^6.
We start at the source square and want to reach the target square.  Each move, we can walk to a 4-directionally adjacent square in the grid that isn't in the given list of blocked squares.
Return true if and only if it is possible to reach the target square through a sequence of moves.
 
Example 1:
Input: blocked = [[0,1],[1,0]], source = [0,0], target = [0,2]
Output: false
Explanation: 
The target square is inaccessible starting from the source square, because we can't walk outside the grid.

Example 2:
Input: blocked = [], source = [0,0], target = [999999,999999]
Output: true
Explanation: 
Because there are no blocked cells, it's possible to reach the target square.

 
Note:

0 <= blocked.length <= 200
blocked[i].length == 2
0 <= blocked[i][j] < 10^6
source.length == target.length == 2
0 <= source[i][j], target[i][j] < 10^6
source != target

```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 isEscapePossible(self, blocked: List[List[int]], source: List[int], target: List[int]) -> bool:\n        bl = {tuple(b) for b in blocked}\n        s0, s1 = source\n        t0, t1 = target\n        s_vis = {(s0, s1)}\n        t_vis = {(t0, t1)}\n        s_q = [(s0, s1)]\n        t_q = [(t0, t1)]\n        while s_q and len(s_vis) < 20010:\n            n0, n1 = s_q.pop()\n            if (n0, n1) == (t0, t1):\n                return True\n            if n0 < 10**6-1 and (n0+1, n1) not in s_vis and (n0+1, n1) not in bl:\n                s_q.append((n0+1, n1))\n                s_vis.add((n0+1, n1))\n            if n0 > 0 and (n0-1, n1) not in s_vis and (n0-1, n1) not in bl:\n                s_q.append((n0-1, n1))\n                s_vis.add((n0-1, n1))\n            if n1 < 10**6-1 and (n0, n1+1) not in s_vis and (n0, n1+1) not in bl:\n                s_q.append((n0, n1+1))\n                s_vis.add((n0, n1+1))\n            if n1 > 0 and (n0, n1-1) not in s_vis and (n0, n1-1) not in bl:\n                s_q.append((n0, n1-1))\n                s_vis.add((n0, n1-1))\n        while t_q and len(t_vis) < 20010:\n            n0, n1 = t_q.pop()\n            if (n0, n1) == (s0, s1):\n                return True\n            if n0 < 10**6-1 and (n0+1, n1) not in t_vis and (n0+1, n1) not in bl:\n                t_q.append((n0+1, n1))\n                t_vis.add((n0+1, n1))\n            if n0 > 0 and (n0-1, n1) not in t_vis and (n0-1, n1) not in bl:\n                t_q.append((n0-1, n1))\n                t_vis.add((n0-1, n1))\n            if n1 < 10**6-1 and (n0, n1+1) not in t_vis and (n0, n1+1) not in bl:\n                t_q.append((n0, n1+1))\n                t_vis.add((n0, n1+1))\n            if n1 > 0 and (n0, n1-1) not in t_vis and (n0, n1-1) not in bl:\n                t_q.append((n0, n1-1))\n                t_vis.add((n0, n1-1))\n\n        return bool(t_q and s_q)\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'isEscapePossible'
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: 4978448