a,b=map(int, input().split())
s=list(input())

if s[a]!="-":
  print("No")
  exit()
  
for i in range(a):
  if s[i]=="-":
    print("No")
    exit()

for i in range(b):
  if s[((a+b)-a-1)+i]=="-":
    print("No")
    exit()

print("Yes")
