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 (3.4.3) (judge verdict: Wrong Answer)

A,B = input().split()
S = input()

s = int(A)+int(B)+1
ans = ""

if len(S) > s or len(S) < s or len(S[int(A)+1:s]):
    ans = "No"

elif S[int(A)] == "-":
    S[int(A)] == 0
    for i in range(int(A)+int(B)+1):
        if S[i].isdigit():
            ans = "Yes"
        else:
            ans = "No"

else:
    ans = "No"

print(ans)