#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;
}
