a,b = map(int, input().split())
s = input()
f = 0
if len(s)==a+b+1:
    for i in range(a):
        if s[i]=="-":
            f = 1
    if s[a]!="-":
        f = 1
    for i in range(a+1,b+1):
        if s[i]=="-":
            f = 1
    if f==0:
        print("Yes")
    else:
        print("No")
else:
    print("No")