#include <iostream>
#include <cstdio>
#include <ctime>
#include <cstdlib>

const int maxn = 1000;

using namespace std;

int main(int argc, char *argv[])
{
    srand(atoi(argv[1]));
    int n = rand() % maxn;
    printf("%d\n", n);
    for (int i = 1; i < n; i++)
        printf("%d %d\n", rand() % i, i);
    return 0;
}