已WA，放心食用

#include <bits/stdc++.h> 
using namespace std;
int main()
{
    int n;
    cin >> n;
    string s1, s2;
    for(int i = 1; i <= n; i++)
    {
        cin >> s1 >> s2;
        s1.insert(s1.length() / 2, s2);
        cout << s1 << endl;
    }
    return 0;
}