#include <iostream>
#include <cstring>
using namespace std;
#define MAX 100
void solve(char first[], int spos_f, int epos_f, char mid[], int spos_m, int epos_m)
{
    int i, root_m;
    if(spos_f > epos_f)
        return;
    for(i = spos_m; i <= epos_m; i++)
        if(first[spos_f] == mid[i])
        {
            root_m = i;
            break;
        }
    solve(first, spos_f + 1, spos_f + (root_m - spos_m), mid, spos_m, root_m - 1);
    solve(first, spos_f + (root_m - spos_m) + 1, epos_f, mid, root_m + 1, epos_m);
    cout << first[spos_f];
}

int main()
{
    char first[MAX], mid[MAX];
    int len;
    cin >> len;
    cin >> first >> mid;
    solve(first, 0, len - 1, mid , 0, len - 1);
    cout << endl;
    return 0;
}

输出： 【第1空】

请填写答案。

{{ input(1) }}