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#include<cstdio>

int k, len, count, next_node, sink;
int binary[33];

int main()
{
    scanf("%d", &k);
    if (k == 1)
    {
        printf("2\n2 -1\n-1 -1\n");
        return 0;
    }
    len = count = 0;
    while (k)
    {
        binary[len++] = k & 1;
        count += k & 1;
        k >>= 1;
    }
    sink = 2 * len + count - 2;
    printf("%d\n", sink);
    next_node = 2;
    if (binary[0]) printf("%d %d\n", next_node++, sink);
    for (int i = 1; i < len - 1; ++i)
    {
        printf("%d %d\n%d -1\n", next_node, next_node + 1, next_node + 1);
        next_node += 2;
        if (binary[i]) printf("%d %d\n", next_node++, sink);
    }
    printf("%d %d\n%d -1\n-1 -1\n", next_node, next_node + 1, next_node + 1);

    return 0;
}