#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  string s;
  cin >> a >> b >> s;
  int c = 0;
  for (size_t i = 0; i < s.length(); i++) {
    if (s[i] == '-') {
      c++;
    }
  }
  if (c == 1) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
