#include <iostream>
#include <vector>
#include<algorithm>

using namespace std;

struct tomb
{
	int a;
	int b;
};
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	int n, m, k;
	cin >> n >> m >> k;
	tomb x;
	vector<tomb> t;
	for (int i = 0; i < m; ++i)
	{
		cin >> x.b;
		x.a = i + 1;
		t.push_back(x);
	}
	sort(t.begin(), t.end(), [](const tomb& g, const tomb& h) { return g.b < h.b; });
	int szam = 0;
	for (int i = 0; i <= n * k and i < m; ++i)
	{
		if (i / k + 1 <= t[i].b) ++szam;
	}
	cout << szam<<"\n";
	for (int i = 0; i <= n * k and i < m; ++i)
	{
		if (i / k + 1 <= t[i].b) cout << t[i].a << " " << i / k + 1 << "\n";
	}
}