#include <bits/stdc++.h>
using namespace std;
int in(int &a, int &b, int &c, int &d) {
  return scanf("%d%d%d%d", &a, &b, &c, &d);
}
int in(int &a, int &b, int &c) { return scanf("%d%d%d", &a, &b, &c); }
int in(int &a, int &b) { return scanf("%d%d", &a, &b); }
int in(long long &a) { return scanf("%lld", &a); }
int in(int &a) { return scanf("%d", &a); }
int in(char *s) { return scanf("%s", s); }
int in(char &s) { return scanf("%c", &s); }
int in(long double &a) { return scanf("%Lf", &a); }
void out(int a) { printf("%d", a); }
void outln(int a) { printf("%d\n", a); }
void out(long long a) { printf("%lld", a); }
void outln(long long a) { printf("%lld\n", a); }
const long double pi = acos((long double)-1);
const long long inf = 0x3f3f3f3f;
const long double eps = 1e-8;
const int N = 2.1e5;
const long long mod = 1e9 + 7;
int sign(long double a) { return a < -eps ? -1 : a > eps; }
int db_cmp(long double a, long double b) { return sign(a - b); }
pair<int, int> ans[1100];
int main() {
  int n;
  in(n);
  int k = n / 2 + 1;
  int x1 = 1, y1 = 0, x2 = k, y2 = k + 1;
  outln(k);
  int l = 0, r = n + 1;
  int fla = 2;
  while (r - l > 1) {
    if (fla == 0) {
      x1++;
      l++;
      ans[l] = pair<int, int>(x1, y1);
    } else if (fla == 1) {
      x2--;
      r--;
      ans[r] = pair<int, int>(x2, y2);
    } else if (fla == 2) {
      y1++;
      l++;
      ans[l] = pair<int, int>(x1, y1);
    } else {
      y2--;
      r--;
      ans[r] = pair<int, int>(x2, y2);
    }
    fla = (fla + 1) % 4;
  }
  for (int i = 1; i <= n; i++) {
    printf("%d %d\n", ans[i].first, ans[i].second);
  }
  return 0;
}
