#include <bits/stdc++.h>
using namespace std;

int main() {
  int n;
  while(cin >> n && n != -1) {
    if(n == 0) {
      cout << 0 << endl;
      continue;
    }
    vector<int> v;
    while(n) {
      v.push_back(n%4);
      n /= 4;
    }
    for(int i = v.size()-1; i >= 0; --i) cout << v[i];
    cout << endl;
  }
  return 0;
}