#include<bits/stdc++.h>
using namespace std;
#define optimise ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)

struct Node {
    int data;
    Node* left;
    Node* right;
};

Node* createNode(int val) {
    Node* newNode = new Node;
    newNode->data = val;
    newNode->left = nullptr;
    newNode->right = nullptr;
    return newNode;
}

Node* insert(Node* root, int val) {
    if (root == nullptr) {
        return createNode(val);
    }

    if (val < root->data) {
        root->left = insert(root->left, val);
    } else {
        root->right = insert(root->right, val);
    }

    return root;
}

void inorderTraversal(Node* root) {
    if (root == nullptr) {
        return;
    }

    inorderTraversal(root->left);
    inorderTraversal(root->right);
    cout << root->data << endl;
}

int main() {
    Node* root = nullptr;
    int val;
    while(1){
            cin>>val;
            if(val == 0) break;
            if(root == nullptr) root = insert(root, val);
            else insert(root, val);
    }
     inorderTraversal(root);
}