#include <bits/stdc++.h>
using namespace std;
char s[110];
int main() {
  int n, m;
  scanf("%s", s);
  n = strlen(s);
  int bus = 0;
  int nit = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'o') bus++;
    if (s[i] == '-') nit++;
  }
  if (bus == 0 || nit == 0) {
    cout << "YES";
    return 0;
  }
  m = nit / bus;
  if (bus * m - nit == 0) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
