#include <bits/stdc++.h>
using namespace std;
vector<int> ke[1001];
int main() {
int n; // n là s? d?nh
cin >> n;
cin.ignore(); // Xóa b? dòng tr?ng sau khi d?c s? d?nh
// Ð?c danh sách k?
for (int i = 1; i <= n; i++) {
string s;
getline(cin, s);
stringstream ss(s);
string token;
while (ss >> token) {
ke[i].push_back(stoi(token));
}
}
// Chuy?n danh sách k? sang danh sách c?nh
cout << "Danh sach canh:\n";
for (int i = 1; i <= n; i++) {
for (int j : ke[i]) {
if (i < j) { // Ch? x? lý c?nh m?t l?n
cout << i << " " << j << "\n";
}
}
}
return 0;
}
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