Language: C++

#![allow(unused_imports, unused_variables, dead_code)]
use std::io::{stdin, Read, StdinLock};
use std::str::FromStr;
use std::fmt::*;
use std::str::*;
use std::cmp::*;
use std::collections::*;

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

fn main() {
    input! {
        n: usize,
        ts: [chars; n],
        m: usize,
        ss: [chars; m],
    };

    let mut p = HashMap::new();
    for t in &ts {
        let i = p.entry(t).or_insert(0);
        *i += 1;
    }
    let mut m = HashMap::new();
    for s in &ss {
        let i = m.entry(s).or_insert(0);
        *i += 1;
    }
    let mut ans: i32 = 0;
    for t in &ts {
        ans = max(ans, *p.entry(t).or_default() - *m.entry(t).or_default());
    }

    println!("{}", ans);
}


Compiler output:
a.cc:1:2: error: invalid preprocessing directive #!
    1 | #![allow(unused_imports, unused_variables, dead_code)]
      |  ^
a.cc:44:10: error: too many decimal points in number
   44 |         (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
      |          ^~~~~~~
a.cc:2:1: error: 'use' does not name a type
    2 | use std::io::{stdin, Read, StdinLock};
      | ^~~
a.cc:3:1: error: 'use' does not name a type
    3 | use std::str::FromStr;
      | ^~~
a.cc:4:1: error: 'use' does not name a type
    4 | use std::fmt::*;
      | ^~~
a.cc:5:1: error: 'use' does not name a type
    5 | use std::str::*;
      | ^~~
a.cc:6:1: error: 'use' does not name a type
    6 | use std::cmp::*;
      | ^~~
a.cc:7:1: error: 'use' does not name a type
    7 | use std::collections::*;
      | ^~~
a.cc:9:1: error: 'macro_rules' does not name a type
    9 | macro_rules! input {
      | ^~~~~~~~~~~
a.cc:29:1: error: 'macro_rules' does not name a type
   29 | macro_rules! input_inner {
      | ^~~~~~~~~~~
a.cc:38:1: error: 'macro_rules' does not name a type
   38 | macro_rules! read_value {
      | ^~~~~~~~~~~
a.cc:60:1: error: 'fn' does not name a type
   60 | fn main() {
      | ^~