#include<stdio.h>
#include<stdlib.h>
struct BiTree
{
    char lc;
    char rc;
} lt[130]; //数组，字母输入后会转化为ASCLL码
char h,h1;
void PreOrderTraverse(char ch)
{
    if(ch=='*') return;
    else printf("%c",ch);
    PreOrderTraverse(lt[ch].lc);
    PreOrderTraverse(lt[ch].rc);
}
int main()
{
    int n;
    h='a';
    scanf("%d",&n);
    getchar();
    scanf("%c",&h1);
    scanf("%c",&lt[h1].lc);
    scanf("%c",&lt[h1].rc);
    for(int i=2; i<=n; i++)
    {
        getchar();
        scanf("%c",&h);
        scanf("%c",&lt[h].lc);
        scanf("%c",&lt[h].rc);
    }
    PreOrderTraverse(h1);
    return 0;
}