#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <complex>
#include <cstring>
#include <cstdlib>
#include <string>
#include <cmath>
#include <queue>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define INF 1<<30

int main() {
  int n;
  while(cin>>n,n!=-1) {
    string s;
    do {
      s += '0' + n % 4;
      n /= 4;
    } while(n != 0);
    reverse(ALL(s));
    cout << s << endl;
  }
}