#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  string str;
  cin >> str;
  int x = count(str.begin(), str.end(), '-');
  int y = count(str.begin(), str.end(), 'o');
  if (y == 0 || x == 0)
    cout << "YES" << endl;
  else if (x < y)
    cout << "NO" << endl;
  else if (x % y == 0)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
