Some people will make friend requests. The list of their ages is given and ages[i] is the age of the ith person. 
Person A will NOT friend request person B (B != A) if any of the following conditions are true:

age[B] <= 0.5 * age[A] + 7
age[B] > age[A]
age[B] > 100 && age[A] < 100

Otherwise, A will friend request B.
Note that if A requests B, B does not necessarily request A.  Also, people will not friend request themselves.
How many total friend requests are made?
Example 1:
Input: [16,16]
Output: 2
Explanation: 2 people friend request each other.

Example 2:
Input: [16,17,18]
Output: 2
Explanation: Friend requests are made 17 -> 16, 18 -> 17.
Example 3:
Input: [20,30,100,110,120]
Output: 3
Explanation: Friend requests are made 110 -> 100, 120 -> 110, 120 -> 100.

 
Notes:

1 <= ages.length <= 20000.
1 <= ages[i] <= 120.

```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 numFriendRequests(self, ages: List[int]) -> int:\n        total_age = 121\n        ageCnt = [0]*total_age\n        prefixSum = [0]*total_age\n        for age in ages:\n            ageCnt[age] += 1\n        for i in range(1, total_age):\n            prefixSum[i] = ageCnt[i] + prefixSum[i-1]\n        res = 0 \n        for i in range(15, total_age):\n            if ageCnt[i] == 0:\n                continue \n            res += ageCnt[i]*(prefixSum[i]-prefixSum[int(i*.5+7)]-1)#)- ageCnt[i]\n        return res '''\n\nclass Solution:\n    def numFriendRequests(self, ages: List[int]) -> int:\n        maxAge = 121 \n        preSum = [0]*maxAge \n        from collections import Counter \n        ageCnt = Counter(ages)\n        for i in range(1, maxAge):\n            preSum[i] += preSum[i-1] + ageCnt[i]\n        res =0 \n        for age in range(15, maxAge):\n            res += (preSum[age]-preSum[int(.5*age+7)]-1) * ageCnt[age]\n        return res \n            \n        \n        \n        '''\n        Person A will NOT friend request person B (B != A) \n        if any of the following conditions are true:\nage[B] <= 0.5 * age[A] + 7\nage[B] > age[A]\nage[B] > 100 && age[A] < 100\n        '''\n        '''from collections import Counter \n        cnt = Counter(ages)\n        res = 0 \n        def request(a,b):\n            return not (b <= .5*a+7 or b>a)\n        for a in cnt:\n            for b in cnt:\n                res += request(a,b)*cnt[a]*(cnt[b]-(a==b))\n        return res '''\n            \n        \n        \n        \n        \n"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'numFriendRequests'
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: 11358