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;


fn read_line() -> String {
    let mut in_str = String::new();
    io::stdin().read_line(&mut in_str).unwrap();
    return in_str
}


fn is_digit(c : char) -> bool {
    return '0' <= c && c <= '9';
}

fn main(){

    let ln1 = read_line();
    let mut lnsw = ln1.split_whitespace(); 

    let a = lnsw.next().unwrap().parse::<i32>().unwrap();
    lnsw.next().unwrap().parse::<i32>().unwrap();
    
    let ln2 = read_line();

    let mut valid : bool = true;
    
    for x in 0..(ln2.len()-1) {
        let c : char = ln2.chars().nth(x).unwrap();
        let ix : i32 = x as i32;
        if 0 <= ix && ix < a {
            if !is_digit(c) {
                valid = false;
            }
        }
        else if ix == a {
            if c != '-' {
                valid = false;
            }
        }
        else {
            if !is_digit(c) {
                valid = false;
            }
        }
    }

    if valid {
        println!("Yes");
    }
    else{
        println!("No");
    }
    
}