C++ :

#include<iostream>
#include<iomanip>
using namespace std;
class  MyTime{
public:
    MyTime();
    MyTime(int N_hour,int N_minute,int N_second);
    void SetTime(int S_hour,int S_minute,int S_second);
    void AddTime(int O_hour,int O_minute,int O_second);
    void MinusTime(int O_hour,int O_minute,int O_second);
    void ShowTime();
private:
    int hour,minute,second;
};

MyTime::MyTime(){
    hour=0,minute=0,second=0;
}
MyTime::MyTime(int N_hour,int N_minute,int N_second){
    hour=N_hour,minute=N_minute,second=N_second;
}
void MyTime::SetTime(int S_hour,int S_minute,int S_second){
    hour=S_hour,minute=S_minute,second=S_second;
}
void MyTime::AddTime(int O_hour,int O_minute,int O_second){
    if ((second+=O_second)>59){
        second-=60;
        minute+=1;
    }
    if ((minute+=O_minute)>59){
        minute-=60;
        hour+=1;
    }
    if ((hour+=O_hour)>23){
        hour-=24;
    }
}
void MyTime::MinusTime(int O_hour,int O_minute,int O_second){
    if ((second-=O_second)<0){
        second+=60;
        minute-=1;
    }
    if ((minute-=O_minute)<0){
        minute+=60;
        hour-=1;
    }
    if ((hour-=O_hour)<0){
        hour+=24;
    }
}
void MyTime::ShowTime(){
    if(hour<12){
        cout<<setw(2)<<setfill('0')<<hour<<":"
            <<setw(2)<<setfill('0')<<minute<<":"
            <<setw(2)<<setfill('0')<<second<<" AM";
    }
    else{
        cout<<setw(2)<<setfill('0')<<hour-12<<":"
            <<setw(2)<<setfill('0')<<minute<<":"
            <<setw(2)<<setfill('0')<<second<<" PM";
    }
    cout<<endl;
    cout<<setw(2)<<setfill('0')<<hour<<":"
        <<setw(2)<<setfill('0')<<minute<<":"
        <<setw(2)<<setfill('0')<<second;
}

int main(){
    int hour,minute,second,O_hour,O_minute,O_second;
    MyTime T1,T2(8,10,30);
    cin>>hour>>minute>>second;
	cin>>O_hour>>O_minute>>O_second;
    T1.ShowTime();
	cout<<endl;    
    T2.ShowTime();
    cout<<endl;
    T1.SetTime(hour,minute,second);
    T1.AddTime(O_hour,O_minute,O_second);
    T2.MinusTime(O_hour,O_minute,O_second);
    T1.ShowTime();  
	cout<<endl;  
    T2.ShowTime();
    return 0;
}