 #include <bits/stdc++.h>
  using namespace std;

 int main(){

   int a;
   int b;
   string s;
   bool check = true;

   cin >> a >> b >> s;

   for(int i = 0;i < s.size();i++){

     if(i == a){
            if(s[i] != '-'){
         check = false;
       }

       if(s[i] > '0' && s[i] < '9'){
         check = false;
       }

     }
   }

     if(check == true){
       cout << "YES" << endl;
     }else{
       cout << "NO" << endl;
     }
     return 0;
   }
 }
