C++ :

#include<cstdio>
#include<iostream>
#include<algorithm>
using namespace std;
struct date
{
    int month;
    int day;
    int year;
}d[500];
int compare(date a,date b)
{
    if(a.year==b.year)
    {
        if(a.month==b.month)
        {
            return a.day<b.day;
        }
        else
        {
            return a.month<b.month;
        }
    }
    else
    {
        return a.year<b.year;
    }
}
int main()
{
    int i,num=0;
    while(scanf("%d/%d/%d",&d[num].month,&d[num].day,&d[num].year)!=EOF)
    {
        num++;
    }
    sort(d,d+num,compare);
    for(i=0;i<num;i++)
    {
        printf("%02d/%02d/%d\n",d[i].month,d[i].day,d[i].year);
    }
}