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