# Task
 let F(N) be the sum square of digits of N. So:
 
 `F(1) = 1, F(3) = 9, F(123) = 14`

 Choose a number A, the sequence {A0, A1, ...} is defined as followed:
  ```
  A0 = A
  A1 = F(A0)
  A2 = F(A1) ...
  ```
  
  if A = 123, we have:
  ```
  123 → 14(1 x 1 + 2 x 2 + 3 x 3)
      → 17(1 x 1 + 4 x 4)
      → 50(1 x 1 + 7 x 7)
      → 25(5 x 5 + 0 x 0)
      → 29(2 x 2 + 5 x 5)
      → 85(2 x 2 + 9 x 9)
      → 89(8 x 8 + 5 x 5)             ---
      → 145(8 x 8 + 9 x 9)             |r
      → 42(1 x 1 + 4 x 4 + 5 x 5)      |e
      → 20(4 x 4 + 2 x 2)              |p
      → 4(2 x 2 + 0 x 0)               |e
      → 16(4 x 4)                      |a
      → 37(1 x 1 + 6 x 6)              |t
      → 58(3 x 3 + 7 x 7)              |
      → 89(5 x 5 + 8 x 8)             --- 
      → ......
  ```

 As you can see, the sequence repeats itself. Interestingly, whatever A is, there's an index such that from it, the sequence repeats again and again.

 Let `G(A)` be the minimum length of the repeat sequence with A0 = A. 

 So `G(85) = 8` (8 number : `89,145,42, 20,4,16,37,58`)

 Your task is to find G(A) and return it.

# Input/Output


 - `[input]` integer `a0`

  the A0 number


 - `[output]` an integer

  the length of the repeat sequence

```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 = 'digits = lambda n: map(int, str(n))\n\ndef repeat_sequence_len(n):\n    seen = []\n    \n    while n not in seen:\n        seen.append(n)\n        n = sum(x*x for x in digits(n))\n    \n    return len(seen) - seen.index(n)'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'repeat_sequence_len'
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: 5790