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