PAT 1006. Sign In and Sign Out

#include<iostream>
#include<string>
using namespace std;
int main(){
  int cnt;cin>>cnt;
  string first,last,in("44:44:44"),out("00:00:00");
  while(cnt--){
    string a,b,c;cin>>a>>b>>c;
    if(b<in){first=a;in=b;};
    if(c>out){last=a;out=c;}
  }
  cout<<first<<' '<<last;
  return 0;
}