#include <fstream>
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>

using namespace std;

ifstream ifs("input.txt");
ofstream ofs("output.txt");

class time{
private:
    int h,m,s;
public:
    time():h(0),m(0),s(0){};
    time(int a,int b,int c):h(a),m(b),s(c){};
    time(string s):
        h((s[0]-'0')*10+(s[1]-'0')),
        m((s[3]-'0')*10+(s[4]-'0')),
        s((s[6]-'0')*10+(s[7]-'0'))
        {};
    const time operator+(const int& sec) const {
        time t(h,m,s);
        t.s+=sec;
        t.m+=t.s/60;
        t.s=t.s%60;
        t.h+=t.m/60;
        t.m=t.m%60;
        return t;
    };
    friend ostream& operator<<(ostream& os, const time& t){
        if(t.h<10)os<<'0';
        os<<t.h<<':';
        if(t.m<10)os<<'0';
        os<<t.m<<':';
        if(t.s<10)os<<'0';
        os<<t.s;
        return os;
    };
    friend istream& operator>>(istream& is, time& t){
        string s;
        is>>s;
        t=s;
        return is;
    };
    const bool operator==(const time t)const{
        return ((t.s+t.m*60+t.h*3600)==(s+m*60+h*3600))?1:0;
    };
    const bool operator!=(const time t)const{
        return ((t.s+t.m*60+t.h*3600)==(s+m*60+h*3600))?0:1;
    };
    const bool operator>(const time t)const{
        return ((t.s+t.m*60+t.h*3600)<(s+m*60+h*3600))?1:0;
    };
    const bool operator<(const time t)const{
        return ((t.s+t.m*60+t.h*3600)<(s+m*60+h*3600))?0:1;
    };
    bool zero(){
        if(h&&m&&s) return true;
        return false;
    };
    void null(){
        h=0;
        m=0;
        s=0;
    };
};

int check(int n,int t,int l,vector<time>& v){
    for(int j=n+1;j<=l;j++)
            if(v[n].zero()||v[j].zero())
                if((v[n]+t)==v[j]){
                    ofs<<v[n]<<'-'<<v[j]<<endl;
                    v[n].null();
                    v[j].null();
                    return 0;
                }
};

int main()
{
    string s;
    int n,t;
    ifs>>n>>t;
    n*=2;
    vector<time>v(n);
    for(int i=0;i<n;i++)ifs>>v[i];
    sort(v.begin(),v.end());
    for(int i=0;i<n-1;i++)check(i,t,n,v);
    return 0;
}