这段程序会输出什么？

#include <iostream>
#include <stdexcept>

struct Guard {
    int id;
    Guard(int value) : id(value) { std::cout << "+" << id << '\n'; }
    ~Guard() { std::cout << "-" << id << '\n'; }
};

void run() {
    Guard first(1);
    Guard second(2);
    throw std::runtime_error("stop");
}

int main() {
    try { run(); }
    catch (const std::exception&) { std::cout << "caught\n"; }
}