#include <bits/stdc++.h>
using namespace std;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
bool debug = false;
int main() {
  int a, b, aa, bb;
  bool ok = true;
  string s;
  cin >> a >> b >> s;
  for (int i = 0; i < int(s.size()); i++) {
    if (s[i] == '-') {
      ok = false;
    } else if (ok) {
      aa++;
    } else {
      bb++;
    }
  }
  if (a == aa && b == bb)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
