Given a list of white pawns on a chessboard (any number of them, meaning from 0 to 64 and with the possibility to be positioned everywhere), determine how many of them have their backs covered by another. 
Pawns attacking upwards since we have only white ones.

Please remember that a pawn attack(and defend as well) only the 2 square on the sides in front of him. https://en.wikipedia.org/wiki/Pawn_(chess)#/media/File:Pawn_(chess)_movements.gif

This is how the chess board coordinates are defined:
ABCDEFGH8♜♞♝♛♚♝♞♜7♟♟♟♟♟♟♟♟65432♙♙♙♙♙♙♙♙1♖♘♗♕♔♗♘♖

```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 = "letters = {\n    'a': ('b',),\n    'b': ('a', 'c',),\n    'c': ('b', 'd',),\n    'd': ('c', 'e',),\n    'e': ('d', 'f',),\n    'f': ('e', 'g',),\n    'g': ('f', 'h',),\n    'h': ('g',),\n}\n\n\ndef get_cells(pawn):\n    x, y = pawn\n    y = int(y)\n    if y < 8:\n        cells = [letter + str(y + 1) for letter in letters[x]]\n        return cells\n    return []\n\n\ndef covered_pawns(pawns):\n    res = set()\n    pawns = set(pawns)\n    for pawn in pawns:\n        cells = get_cells(pawn)\n        for cell in cells:\n            if cell in pawns:\n                res.add(cell)\n    return len(res)\n"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'covered_pawns'
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: 7140