#include <iostream>
#include <algorithm>

using namespace std;

struct rendeles {
    int sor;
    int hat;
};

int rule(rendeles x, rendeles y) {
    if(x.hat<=y.hat) return 1;
    else return 0;
}

int main() {
    int n, m=0, k;
    cin >> n >> m >> k;
    rendeles r[10001];
    for(int i=1; i<=m; i++) {
        cin >> r[i].hat;
        r[i].sor=i;
    }
    sort(r+1, r+m+1, rule);

    /*for(int i=1; i<=m; i++) {
        cout << r[i].sor << ", " << r[i].hat << endl;
    }*/

    rendeles jo[10001];

    int t=0, nc=1, lim=0, veg=0, rg=1, jg=1;
    while(veg==0 && rg<=m && nc<=n) {
        if(lim>k) {
            nc++;
            lim=0;
        }
        else {
            if(r[rg].hat>=nc) {
                jo[jg]=r[rg];
                jg++;
                rg++;
                lim++;
                t++;
            }
            else {
                veg=1;
            }
        }
    }
    cout << t << endl;
    for(int i=1; i<jg; i++) {
        cout << jo[i].sor << " " << jo[i].hat << endl;
    }


    return 0;
}