#include<iostream>
#include<string>
#include<algorithm>
using namespace std;
string s;
bool check(char c){
for(int i=0;i<9;i+=3){
if(s[i]==s[i+1]&&s[i+1]==s[i+2]&&s[i]==c){
return true;
}
}
for(int i=0;i<3;i++){
if(s[i]==c&&s[i+3]==c&&s[i+6]==c){
return true;
}
}
if(s[0]==s[4]&&s[4]==s[8]&&s[0]==c){
return true;
}
if(s[2]==s[4]&&s[4]==s[6]&&s[2]==c){
return true;
}
return false;
}
int main(){
while(cin>>s){
bool o = check('o');
bool x = check('x');
if(o){
cout<<"o"<<endl;
}
if(x){
cout<<"x"<<endl;
}
if(!o&&!x){
cout<<"d"<<endl;
}
}
}