Language: C

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let mut s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

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

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

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

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

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

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

fn min(a: &i64, b: &i64) -> i64 {
    if *a <= 0i64 {
        *b
    } else if *b <= 0i64 {
        *a
    } else if *a < *b {
        *a
    } else {
        *b
    }
}

fn max(a: &i64, b: &i64) -> i64 {
    if *a < *b {
        *b
    } else {
        *a
    }
}

fn abs(a: &i64, b: &i64) -> i64 {
    if *a - *b <= 0 {
        *b - *a
    } else {
        *a - *b
    }
}

fn main() {
    input! {
        n: chars
    }
    print!("{}", if n[0] == '7' || n[1] == '7' || n[2] == '7' {"Yes".to_string()} else {"No".to_string()})
}


Compiler output:
main.c:1:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '!' token
    1 | macro_rules! input {
      |            ^
main.c:18:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '!' token
   18 | macro_rules! input_inner {
      |            ^
main.c:28:12: error: expected '=', ',', ';', 'asm' or '__attribute__' before '!' token
   28 | macro_rules! read_value {
      |            ^
main.c:34:10: error: too many decimal points in number
   34 |         (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
      |          ^~~~~~~
main.c:50:1: error: unknown type name 'fn'
   50 | fn min(a: &i64, b: &i64) -> i64 {
      | ^~
main.c:50:9: error: expected ')' before ':' token
   50 | fn min(a: &i64, b: &i64) -> i64 {
      |         ^
      |         )
main.c:51:14: error: invalid suffix "i64" on integer constant
   51 |     if *a <= 0i64 {
      |              ^~~~
main.c:53:21: error: invalid suffix "i64" on integer constant
   53 |     } else if *b <= 0i64 {
      |                     ^~~~
main.c:62:1: error: unknown type name 'fn'
   62 | fn max(a: &i64, b: &i64) -> i64 {
      | ^~
main.c:62:9: error: expected ')' before ':' token
   62 | fn max(a: &i64, b: &i64) -> i64 {
      |         ^
      |         )
main.c:70:1: error: unknown type name 'fn'
   70 | fn abs(a: &i64, b: &i64) -> i64 {
      | ^~
main.c:70:9: error: expected ')' before ':' token
   70 | fn abs(a: &i64, b: &i64) -> i64 {
      |         ^
      |         )
main.c:78:1: error: unknown type name 'fn'
   78 | fn main() {
      | ^~
main.c: In function 'main':
main.c:79:5: error: 'input' undeclared (first use in this function); did you mean 'int'?
   79 |     input! {
      |     ^~~~~
      |     int
main.c:79:5: note: each undeclared identifier is reported only once for each function it appears in
main.c:79:10: error: expected ';' before '!' token
   79 |     input! {
      |          ^
      |          ;