#include <cstdio>

int main() {
  freopen("tije.in", "r", stdin);
  freopen("tije.out", "w", stdout);
  
  int N;
  scanf("%d", &N);
  for(int i = N - 1; i >= 1; i--) {
    for (int j = N; j >= 1; j--) {
      for (int k = 1; k <= i; k++) {
        printf("%d %d\n", j, j + 1);
      }
    }
    for (int j = 1; j <= i; j++) {
      printf("%d %d\n", N + 1, 1);
    }
  }
  return 0;
}