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