#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int a, b;
  char s[10];
  cin >> a;
  cin >> b;
  cin >> s;
  if (strlen(s) != a + b + 1) {
    cout << "No" << endl;
    return 0;
  }
  for (int i = 0; i < strlen(s); i++) {
    if (a > 0) {
      if (s[i] == '-') {
        cout << "No" << endl;
        return 0;
      }
      a--;
    } else if (a == 0) {
      if (s[i] != '-') {
        cout << "No" << endl;
        return 0;
      }
      a--;
    } else {
      if (s[i] == '-') {
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
