C++ :

#include <bits/stdc++.h>
using namespace std;
struct s
{
	int number;
	int score;
};
int main()
{
	int n,sum=0,i;
	double ave;
	s student[105];
	cin>>n;
	for(i=1;i<=n;i++)
	{
		cin>>student[i].number>>student[i].score;
		sum+=student[i].score;
	}
	ave=sum*1.0/n;
	for(i=1;i<=n;i++)
	{
		cout<<student[i].number<<" "<<student[i].score<<" ";
		if(student[i].score>=ave+10)cout<<"A"<<endl;
		else if(student[i].score<=ave-10)cout<<"C"<<endl;
		else cout<<"B"<<endl;
	}
	return 0;
}

Pascal :

var
a:array[1..100] of longint;
b:array[1..100] of longint;
d:array[1..100] of char;
n,i,s:longint;
begin
read(n);
for i:=1 to n do
read(a[i],b[i]);
for i:=1 to n do
s:=s+b[i];
s:=s div n;
for i:=1 to n do
if b[i]+10<=s then d[i]:='C' else if b[i]-10>=s then d[i]:='A' else d[i]:='B';
for i:=1 to n do
writeln(a[i],' ',b[i],' ',d[i]);
end.