#include <vector>
#include <iostream>
#include <iomanip>
#include <algorithm>
using namespace std;
int main()
{
vector<int> a = { 0, 1, 2, 3, 4 };
vector<int> &c = a;
for(auto i: a) cout << i << " "; cout << endl;
swap(c[2],c[3]);
for(auto i: a) cout << i << " "; cout << endl;
}
I2luY2x1ZGUgPHZlY3Rvcj4KI2luY2x1ZGUgPGlvc3RyZWFtPgojaW5jbHVkZSA8aW9tYW5pcD4KI2luY2x1ZGUgPGFsZ29yaXRobT4KCnVzaW5nIG5hbWVzcGFjZSBzdGQ7CgppbnQgbWFpbigpCnsKICAgIHZlY3RvcjxpbnQ+IGEgPSB7IDAsIDEsIDIsIDMsIDQgfTsKICAgIHZlY3RvcjxpbnQ+ICZjID0gYTsKCiAgICBmb3IoYXV0byBpOiBhKSBjb3V0IDw8IGkgPDwgIiAiOyBjb3V0IDw8IGVuZGw7CgogICAgc3dhcChjWzJdLGNbM10pOwoKICAgIGZvcihhdXRvIGk6IGEpIGNvdXQgPDwgaSA8PCAiICI7IGNvdXQgPDwgZW5kbDsKCn0KCg==