#include <bits/stdc++.h>
using namespace std;
int a, b, t, f;
string s;
int main() {
  cin >> a >> b;
  cin >> s;
  for (int i = 0; i < (a + b + 1); i++)
    if (s[i] != '0' && s[i] != '1' && s[i] != '2' && s[i] != '3' &&
        s[i] != '4' && s[i] != '5' && s[i] != '6' && s[i] != '7' &&
        s[i] != '8' && s[i] != '9') {
      t++;
      f = i;
    }
  if (t == 1 && s[f] == '-')
    cout << "YES";
  else
    cout << "NO";
}
