#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n, k;
    cin >> n >> k;
    int a;
    int retcount = 0;

    vector <int> ret(0);

    for (int i=0; i<n; i++){
        cin >> a;
        if (a==1){
            ret.push_back(i);
            retcount++;
        }
    }
    if (ret.size()<k || retcount<k){
        cout << 0;
        return 0;
    }  
    
    for (int i=0; i<ret.size()-k+1; i++){
        for (int j=i+k-1; j<ret.size(); j++){

            cout << ret[i]+1 << "-" << ret[j]+1;
            if (j<ret.size()-1){
                cout << ", ";
            }
        }


        if (i<ret.size()-k){
            cout << ", ";
        }
    }

    
}