#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
int const INF = 1e9;
ll const INF_LL = 1e18;
ld const eps = 1e-8;
ld const PI = acos(-1);

struct song{
    int id; int val;
    song () {};
    song(int const& ind, int const& v) {id = ind; val = v;}
    bool operator < (song const& a) const{
        if (val != a.val) return val < a.val;
        return id < a.id;
    }
};

string names[1000000];
vector <song> gleb;

int main()
{
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    int n, k;
    scanf("%d %d\n", &n, &k);
    for (int i = 0; i < n; i++) {
        int q;
        cin >> names[i];
        scanf(" %d\n", &q);
        //cin >> names[i] >> q;
        gleb.push_back(song(i, q));
    }
    random_shuffle(gleb.begin(), gleb.end());
    sort(gleb.begin(), gleb.end());
    for (int i = gleb.size() - 1; i > gleb.size() - k; i--) cout << names[gleb[i].id] << "-";
    cout << names[gleb[gleb.size() - k].id];
    return 0;
}