关于set的问题求助

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <set>
using namespace std;
struct node {
	string x, y;
};
set <node> s;
void init()
{
	s.insert(node{ "potato", "persimmon" });
	s.insert(node{ "egg", "glucide" });
	s.insert(node{ "onion", "honey" });
	s.insert(node{ "bean-curd", "honey" });
	s.insert(node{ "radish", "agaric" });
	s.insert(node{ "taro", "banana" });
	s.insert(node{ "pignut", "cucumber" });
	s.insert(node{ "beef", "chestnut" });
	s.insert(node{ "rabbit", "celery" });
	s.insert(node{ "crab", "persimmon" });
	s.insert(node{ "carp", "liquorice" });
}