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