#include <bits/stdc++.h>
using namespace std;
struct tim{
    int h1, m1, s1, h2, m2, s2;
}t[100000];
bool cmp(tim a, tim b)
{
    if ( a.h1 != b.h1 )
        return a.h1 < b.h1;
    else if ( a.m1 != b.m1 )
        return a.m1 < b.m1;
    else
        return a.s1 < b.s1;
};

int main(void)
{
    int n;
    cin >> n;
    for ( int i = 0; i < n; i ++ ) {
        scanf("%d:%d:%d - %d:%d:%d", &t[i].h1, &t[i].m1, &t[i].s1, &t[i].h2, &t[i].m2, &t[i].s2);
    }
    sort(t, t + n, cmp);
    if ( t[0].h1 != 0 || t[0].m1 != 0 || t[0].s1 != 0 ) {
        printf("00:00:00 - %02d:%02d:%02d\n", t[0].h1, t[0].m1, t[0].s1);
    }
    for ( int i = 0; i < n - 1; i ++ ) {
        if ( t[i].h2 != t[i+1].h1 || t[i].m2 != t[i+1].m1 || t[i].s2 != t[i+1].s1 )
            printf("%02d:%02d:%02d - %02d:%02d:%02d\n", t[i].h2, t[i].m2, t[i].s2, t[i+1].h1, t[i+1].m1, t[i+1].s1);
    }
    if ( t[n-1].h2 != 23 || t[n-1].m2 != 59 || t[n-1].s2 != 59 )
        printf("%02d:%02d:%02d - 23:59:59\n", t[n-1].h2, t[n-1].m2, t[n-1].s2);

    return 0;
}