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::*;

// const MOD: i32 = 1000000007;

fn read<T: FromStr>() -> Option<T> {
    let stdin = stdin();
    let s = stdin
        .bytes()
        .map(|c| c.unwrap() as char)
        .take_while(|c| !c.is_whitespace())
        .collect::<String>();
    s.parse::<T>().ok()
}

fn main() {
    let a: usize = read().unwrap();
    let b: usize = read().unwrap();
    let s: String = read().unwrap();

    for i in 0..a {
        match s.chars().nth(i).unwrap() {
            '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' | '0' => continue,
            _ => {
                println!("No");
                return;
            }
        }
    }
    if s.chars().nth(a).unwrap() != '-' {
        println!("No");
        return;
    }
    for i in a + 1..(a + 1 + b) {
        match s.chars().nth(i).unwrap() {
            '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' | '0' => continue,
            _ => {
                println!("No");
                return;
            }
        }
    }
    println!("Yes");
}