#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<char> v;
  char s[100008];
  cin >> s;
  if (strlen(s) % 2 == 1)
    cout << "no\n";
  else {
    int i, n;
    for (i = 0; s[i]; i++) v.push_back(s[i]);
    n = v.size();
    for (i = 0; i < v.size() - 1;)
      if (v[i] == v[i + 1]) {
        v.erase(v.begin() + i + 1);
        v.erase(v.begin() + i);
        i--;
        if (i < 0) i = 0;
        n = v.size();
        if (v.size() == 0) break;
      } else
        i++;
    if (n == 0)
      cout << "yes\n";
    else
      cout << "no\n";
  }
  return 0;
}
