#include <iostream>
#include <string>
using namespace std;
bool in(char s){
  if(s=="1" || s=="2" || s=="3" || s=="4" || s=="5" || s=="6" || s=="7" || s=="8" || s=="9" || s=="0")
    return true;
}
int main(){
  int a,b;
  string s;
  cin >> a >> b >> s;
  for(int i=0;i<a+b+1;i++)
    if(i!=a){
      if(!in(s[i]){
         cout << "No" << endl;
         return 0;
      }
    }
    else
      if(s[i]!='-'){
         cout << "No" << endl;
         return 0;
      }
   cout << "yes" << endl;
}