1 files changed, 32 insertions, 0 deletions
diff --git a/codeforces/BanBan/main.cpp b/codeforces/BanBan/main.cpp
new file mode 100644
index 0000000..abe1f05
--- /dev/null
+++ b/codeforces/BanBan/main.cpp
@@ -0,0 +1,32 @@
+#include<bits/stdc++.h>
+
+using namespace std;
+
+int main () {
+	ios_base::sync_with_stdio(false);
+	cin.tie(NULL);
+	int tt;
+	cin >> tt;
+	while(tt--){
+    int n;
+    cin >> n;
+    if (n == 1) {
+      cout << n << '\n' << 1 << " " << 2 << '\n';
+    } else {
+      cout << n - 1 << '\n';
+      vector<int> v(n);
+      int cnt = 0;
+      for (int i = 0; cnt != n - 1 && i < n; i++) {
+        if((3 * n - 1 - i) % 3 != 0) {
+          cerr << (3 * n - 1 - i) << endl;
+          v[i] = (3 * n - 1 - i);
+          cnt++;
+        }
+      }
+      // cerr << "n - 1 " << n - 1 << endl;
+      for (int i = 0; i < n - 1; i++) {
+        cout << i * 3  + 1 << " " << v[i] + 1 << endl;
+      }
+    }
+	}
+}