#include <iostream>
#include <algorithm>

using namespace std;

struct rendeles {
    int sor, hat;
};

bool rule(rendeles x, rendeles y) {
    return x.hat<y.hat;
}

int main() {
    int n, m, k;
    cin >> n >> m >> k;
    rendeles a[10001];
    for(int i=1; i<=m; i++) {
        cin >> a[i].hat;
        a[i].sor=i;
    }
    sort(a+1, a+m+1, rule);
    
    ///until here its the exact same, except for the fact that shes using a vector.
    //she is using a struct too, with the same values: ind=sor, ido=hat
    //r is a for her, jo is b. imma change this too, to make things easier for myself

    rendeles b[10001];

    //lets change this while to check each day

    int t=0, nc=1, lim=0, veg=0, ag=1, bg=1;
    while(nc<=n) {
        while(a[ag].hat>=nc && lim<k && ag<=m) {
            b[bg].sor=a[ag].sor;
            b[bg].hat=nc;
            bg++;
            ag++;
            lim++;
        }
        nc++;
    }
    cout << bg-1 << endl;
    for(int i=1; i<jg; i++) {
        cout << b[i].sor << " " << b[i].hat;
    }
    return 0;
}