#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  cin >> a >> b;
  string s;
  cin >> s;
  if (s.size() != (a + b + 1)) {
    cout << "NO" << endl;
    system("pause");
    return 0;
  } else if (s[a] != '-') {
    cout << "NO" << endl;
    system("pause");
    return 0;
  } else
    s[a] = 5;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] > 57) {
      cout << "NO" << endl;
      system("pause");
      return 0;
    }
  }
  cout << "YES" << endl;
  system("pause");
  return 0;
}
