#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base ::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int A, B;
  string S;
  cin >> A >> B >> S;
  int cnt = 0;
  for (char e : S)
    if (e == '-') cnt++;
  if (cnt == 1)
    cout << "Yes";
  else
    cout << "No";
  return 0;
}
