#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  int a = 0, b = 0;
  for (int i = 0; i < (int)s.size(); i++) {
    if (s[i] == 'o')
      a++;
    else
      b++;
  }
  if (!a or !b)
    puts("YES");
  else if (b % a == 0)
    puts("YES");
  else
    puts("NO");
  return 0;
}
