PAT 1006 Sign In and Sign Out

#include<iostream>
#include<cstring>
using namespace std;


int main()
{
	char stu_in[15],stu_out[15],stu[15];
	char sign_in[10] = "23:59:59";
	char sign_out[10] = "00:00:00";
	char tmp_in[10],tmp_out[10];
	int num,i;

	cin>>num;
	for(i=0; i<num; i++)
	{
		cin>>stu>>tmp_in>>tmp_out;
		if(strcmp(tmp_in,sign_in) <= 0)
		{
			strcpy(stu_in,stu);
			strcpy(sign_in,tmp_in);
		}
		if(strcmp(tmp_out, sign_out) >= 0)
		{
			strcpy(stu_out,stu);
			strcpy(sign_out,tmp_out);
		}
	}
	cout<<stu_in<<" "<<stu_out<<endl;
	return 0;
}