There is a strange printer with the following two special requirements:

On each turn, the printer will print a solid rectangular pattern of a single color on the grid. This will cover up the existing colors in the rectangle.
Once the printer has used a color for the above operation, the same color cannot be used again.

You are given a m x n matrix targetGrid, where targetGrid[row][col] is the color in the position (row, col) of the grid.
Return true if it is possible to print the matrix targetGrid, otherwise, return false.
 
Example 1:

Input: targetGrid = [[1,1,1,1],[1,2,2,1],[1,2,2,1],[1,1,1,1]]
Output: true

Example 2:

Input: targetGrid = [[1,1,1,1],[1,1,3,3],[1,1,3,4],[5,5,1,4]]
Output: true

Example 3:
Input: targetGrid = [[1,2,1],[2,1,2],[1,2,1]]
Output: false
Explanation: It is impossible to form targetGrid because it is not allowed to print the same color in different turns.
Example 4:
Input: targetGrid = [[1,1,1],[3,1,3]]
Output: false

 
Constraints:

m == targetGrid.length
n == targetGrid[i].length
1 <= m, n <= 60
1 <= targetGrid[row][col] <= 60

```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 = "import queue\nclass Solution:\n    def isPrintable(self, targetGrid: List[List[int]]) -> bool:\n        color_bounds = {}\n        for i, row in enumerate(targetGrid):\n            for j, color in enumerate(row):\n                if not color in color_bounds:\n                    color_bounds[color] = {'row': [1e6,-1e6], 'col': [1e6,-1e6]}\n                color_bounds[color]['row'][0] = min(color_bounds[color]['row'][0], i)\n                color_bounds[color]['row'][1] = max(color_bounds[color]['row'][1], i)\n                color_bounds[color]['col'][0] = min(color_bounds[color]['col'][0], j)\n                color_bounds[color]['col'][1] = max(color_bounds[color]['col'][1], j)\n        graph = collections.defaultdict(list)\n        degree = Counter()\n        for color, bounds in list(color_bounds.items()):\n            seen = set()\n            for i in range(bounds['row'][0], bounds['row'][1] + 1):\n                for j in range(bounds['col'][0], bounds['col'][1] + 1):\n                    other_color = targetGrid[i][j]\n                    if other_color != color and other_color not in seen:\n                        seen.add(other_color)\n                        graph[other_color].append(color)\n                        degree[color] += 1\n        q = queue.Queue()\n        for color in list(color_bounds.keys()):\n            if degree[color] == 0:\n                q.put(color)\n        processed_nodes = 0\n        while not q.empty():\n            color = q.get()\n            processed_nodes += 1\n            for next_color in graph[color]:\n                degree[next_color] -= 1\n                if degree[next_color] == 0:\n                    q.put(next_color)\n        return processed_nodes == len(color_bounds)\n            \n"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'isPrintable'
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: 17880