def slove(a, b, s):
    for i in range(a + b + 1):
        if i == a:
            pass
        else:
            if s[i].isdigit() == False:
                return "No"
    return "Yes"

if __name__ == "__main__":
    ab = input().split()
    a = int(ab[0])
    b = int(ab[1])
    s = list(input())

    print(slove(a, b, s))