#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  string s;
  cin >> a >> b;
  cin >> s;
  int flag = 1;
  int left = 0;
  int right = -1;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == '-') flag = 2;
    if (flag == 1)
      left++;
    else if (flag == 2)
      right++;
  }
  if (left == a && right == b)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
