#include <cstdio>
int v[30], s, son[30][2];
bool vis[30];
void preorder(int u)
{
    if (u == '*' - 'a' + 1)
        return;
    v[s++] = u + 'a' - 1;
    preorder(son[u][0]);
    preorder(son[u][1]);
}
int main()
{
    char a, b, c;
    int n, root;
    scanf("%d\n", &n);
    for (int i = 0; i < n; i++)
    {
        a = getchar(), b = getchar(), c = getchar();
        getchar();
        son[a - 'a' + 1][0] = b - 'a' + 1;
        son[a - 'a' + 1][1] = c - 'a' + 1;
        vis[b - 'a' + 1] = 1;
        vis[c - 'a' + 1] = 1;
    }
    for (int i = 1; i <= 26; i++)
        if (vis[i] == 0)
        {
            root = i;
            break;
        }
    preorder(root);
    for (int i = 0; i < s; i++)
        putchar(v[i]);
    return 0;
}