技术类有第一题ac的大佬么？

为什么我的一点都通过不了，而且怎么看都不知道错哪啦。

代码附上：

#include <iostream>
#include <set>
#include <vector>
using namespace std;
int main(){
    int n, m, num;
    set<int> a;
    while (cin >> n){
        a.clear();
        for (int i = 0; i<n; i++){
            cin >> num;
            a.insert(num);
        }
        cin >> m;
        for (int i = 0; i<m; i++){
            cin >> num;
            a.insert(num);
        }
        set<int>::iterator ite1 = a.begin();
        set<int>::iterator ite2 = a.end();
        vector<int> b;
        for (; ite1 != ite2; ite1++)
        {
            b.push_back(*ite1);
        }
        if (b.size() & 1 == 1)
            cout << b[b.size() / 2] << endl;
        else
            cout << (b[b.size() / 2] + b[b.size() / 2 - 1]) / 2.0 << endl;
    }

    return 0;
}