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