#include <iostream>
#include <vector>
#include <list>
#include <algorithm>
#include <set>
#include <queue>
#include <stack>
#include <string>
#include <sstream>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#define rep(i, n) for(int i = 0; i < n; i ++)
#define COUNT(i, n) for(int i = 1; i <= n; i ++)
#define ITER(c) __typeof((c).begin())
#define each(c, it) for(ITER(c) it =(c).begin(); it!=(c).end(); it++)
#define ALL(c) c.begin(), c.end()
#define mp make_pair
#define pb push_back
#define MEMSET(v, h) memset((v), h, sizeof(v))
 
using namespace std; 

typedef pair<int, int> pii;
typedef long long ll;
typedef vector<int> vi;
typedef vector<string> vs;

const int INF = 1 << 24;
const string L = "ox";

int main(void){
    char res;
    for(string in; res = 'd', cin >> in; cout << res << endl){
        rep(i, 2)
            rep(m, 2){
                int cnt;
                rep(j, 3){
                    cnt = 0;
                    rep(k, 3) if(in.at((m ? j:k) + 3 * (m ? k:j)) == L.at(i)) cnt ++;
                    if(cnt == 3) res = L.at(i);
                }
                cnt = 0;
                rep(j, 3){
                    if(in.at(2 * m + (m ? 2:4) * j) == L.at(i)) cnt ++;
                }
                if(cnt == 3) res = L.at(i);
            }
    }
 
    return 0;
}