#include<iostream>
#include<iomanip>
#include<algorithm>
#include<array>
#include<bitset>
#include<cassert>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<numeric>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=(n)-1;i>=0;i--)
#define ALL(a) (a).begin(),(a).end()
#define DUMP(o) {cerr<<#o<<" "<<o<<endl;}
#define DUMPC(o) {cerr<<#o; for(auto &e:(o))cerr<<" "<<e;cerr<<endl;}
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
const int MOD = 1e9 + 7;

signed main() {
	for (string s; cin >> s;) {
		string ans = "d";
		REP(i, 3) {
			if (s[0 + i * 3] == s[1 + i * 3] && s[1 + i * 3] == s[2 + i * 3]) {
				if (s[0 + i * 3] == 'o')ans = "o";
				if (s[0 + i * 3] == 'x')ans = "x";
			}
		}
		REP(i, 3) {
			if (s[0 + i] == s[3 + i] && s[3 + i] == s[6 + i]) {
				if (s[0 + i] == 'o')ans = "o";
				if (s[0 + i] == 'x')ans = "x";
			}
		}
		if (s[0] == s[4] && s[4] == s[8]) {
			if (s[0] == 'o')ans = "o";
			if (s[0] == 'x')ans = "x";
		}
		if (s[2] == s[4] && s[4] == s[6]) {
			if (s[2] == 'o')ans = "o";
			if (s[2] == 'x')ans = "x";
		}
		cout << ans << endl;
	}
	return 0;
}