#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <queue>
#define endl "\n"
using namespace std;

typedef struct BiTNode {
    char data;
    BiTNode* lchild,* rchild;
};

void create(BiTNode* T) {
    char ch;
    scanf("%c", &ch);
    if (ch == '*')T = NULL;
    else{
        T->data = ch;
        create(T->lchild);
        create(T->rchild);
    }
}

void cen(BiTNode *bt){
    queue<BiTNode*> pr;
    if(bt!=NULL){
        pr.push(bt);
    }
    while(!pr.empty()){
        cout<<pr.front()->data;
        if(pr.front()->lchild!=NULL){
            pr.push(pr.front()->lchild);
        }
        if(pr.front()->rchild!=NULL){
            pr.push(pr.front()->rchild);
        }
        pr.pop();
    }
    return;
}

int main() {
    BiTNode* T;
    create(T);
    cen(T);
    return 0;
}