A, B = map(int, input().split())
s = input()
for i in range(len(s)):
    if i<A and s[i]=='-':
        print("No")
        exit()
    elif i==A and s[i]!='-':
        print("No")
        exit()
    elif A<i<B and s[i]=='-':
        print("No")
        exit()
print("Yes")
