var
  a,b,i:longint;
  s:string;
begin
  readln(a,b);
  readln(s);
  if s[a+1]<>'-' then begin writeln('No');halt; end;
  for i:=1 to a+b do
   if s[i]='-' then begin writeln('No');halt; end;
  writeln('Yes');
end.