C :

#include<stdio.h>
int main()
{
	int m,n,f;
	f=0;
	char a[10];
	gets(a);
	m=(a[0]-48)*10+a[1]-48;
	n=(a[3]-48)*10+a[4]-48;
	if(m>12)
	{
		m=m-12;
		f=1;
	}
	printf("%02d",m);
	printf(":");
	printf("%02d ",n);
	if(f==0)
	printf("AM\n");
	else
	printf("PM\n");
	getchar();
	
	
}

C++ :

#include<iostream>
using namespace std;
int main()
{
    int a;
    int b;
    char c;
    cin>>a>>c>>b;
    if(a > 12)
    {
       if (a == 24)
       {
           a = 0;
           if (b == 0)
           {
               cout<<"00"<<c<<"0"<<b<<" AM"<<endl;
           }
           else
           {
              cout<<"00"<<c<<b<<" AM"<<endl;
           }

       }
       else
       {
           a -= 12;
           cout<<"0"<<a<<c<<b<<" PM"<<endl;
       }
    }
    else
    {
     cout<<"0"<<a<<c<<b<<" AM"<<endl;
    }
    return 0;
}