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 Python (2.7.6) (judge verdict: Accepted)

# -*- coding: utf-8 -*-

import sys

a, b = [int(e) for e in raw_input().split()]
s = raw_input().split()[0]

sa = s[:a]
sh = s[a:a+1]
sb = s[a+1:]

if len(sa) == a:
    if  sa.isdigit():
        if sh == '-':
            if len(sb) == b:
                if sb.isdigit():
                    sys.stdout.write('Yes\n')
                    sys.stdout.flush()
                    sys.exit(0)

sys.stdout.write('No\n')
sys.stdout.flush()