#B Postal Code
a , b = map(int,input().split())
c = input()
d = len(c)
e = 0
for i in range(d):
    if c[i] =="-" and i != a:
        e = e + 1
if a+b+1 == d and c[a] =="-" and e > 0:
    
    print("Yes")
else:
    print("No")