Problem:
Score : 200 points

Problem Statement

The postal code in Atcoder Kingdom is A+B+1 characters long, its (A+1)-th character is a hyphen -, and the other characters are digits from 0 through 9.

You are given a string S. Determine whether it follows the postal code format in Atcoder Kingdom.

Constraints

1≤A,B≤5

|S|=A+B+1

S consists of - and digits from 0 through 9.

Input

Input is given from Standard Input in the following format:

A B
S

Output

Print Yes if S follows the postal code format in AtCoder Kingdom; print No otherwise.

Sample Input 1

3 4
269-6650

Sample Output 1

Yes

The (A+1)-th character of S is -, and the other characters are digits from 0 through 9, so it follows the format.

Sample Input 2

1 1
---

Sample Output 2

No

S contains unnecessary -s other than the (A+1)-th character, so it does not follow the format.

Sample Input 3

1 2
7444

Sample Output 3

No

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::io::*;
use std::str::FromStr;

#[allow(unused_macros)]
macro_rules! scan {
  ($e:expr; $t:ty) => {
    $e.get::<$t>()
  };
  ($e:expr; $($t:ty), *) => {
    ($($e.get::<$t>(),)*)
  };
  ($e:expr => $i:expr; $t:ty) => {
    (0..$i).map(|_| $e.get::<$t>()).collect::<Vec<$t>>()
  };
  ($e:expr => $row:expr, $col:expr; $t:ty) => {
    (0..$i).map(|_| scan!($e => $col; $t)).collect::<Vec<$t>>()
  }
}

struct Scanner<R: Read> {
  reader: R
}

#[allow(dead_code)]
impl<R: Read> Scanner<R> {
  fn new(reader: R) -> Scanner<R> {
    Scanner { reader: reader }
  }
  fn safe_get<T: FromStr>(&mut self) -> Option<T> {
    let token = self.reader.by_ref().bytes().map(|c| c.unwrap() as char)
      .skip_while(|c| c.is_whitespace())
      .take_while(|c| !c.is_whitespace())
      .collect::<String>();
    if token.is_empty() { None } else { token.parse().ok() }
  }
  fn get<T: FromStr>(&mut self) -> T {
    if let Some(v) = self.safe_get() { v } else {
      writeln!(stderr(), "Terminated with EOF").unwrap();
      std::process::exit(0);
    }
  }
}

trait Writable {
  fn write(&self, sep: &'static str) -> String;
}

impl<T: ToString> Writable for Vec<T> {
  fn write(&self, sep: &'static str) -> String {
    self.iter().map(|e| e.to_string()).collect::<Vec<String>>().join(sep)
  }
}

fn main() {
  let cin = stdin();
  let cin = cin.lock();
  let mut sc = Scanner::new(cin);
  let (a, _b, s) = scan!(sc; usize, i32, String);
  let hyphen = s.chars().filter(|&c| c == '-').count();
  if hyphen != 1 {
    println!("No");
    return;
  }
  let hyphen_pos = s.chars().position(|c| c == '-').unwrap();
  println!("{}", if a == hyphen_pos { "Yes" } else { "No" });
}