#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
int n,sh,sm,eh,em;
bool f[200000];
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		scanf("%2d%2d-%2d%2d",&sh,&sm,&eh,&em);
		while(sm%5)
			sm--;
		while(em%5)
			em++;
		for(int i=sh*60+sm;i<=eh*60+em;i++)
			f[i]=1;
	}
	bool flag=0;
	for(int i=0;i<=24*60;i++)
		if(f[i]&&!flag){
			sh=i/60;
			sm=i%60;
			flag=1;
		}else if(flag&&!f[i]){
			printf("%02d%02d-%02d%02d\n",sh,sm,i/60,i%60-1);
			flag=0;
		}
	return 0;
}