C++ :

#include<cstdio>
#include<iostream>
#include<cstring>
//#include<>
using namespace std;
int main()
{
	int l,r,tot=0;
	cin>>l>>r;
	for(int i=l;i<=r;i++)
	{
		int x=i;
		while(x>0)
		{
			if(x%10==2) tot++;
			x=x/10;
		}
	}
	cout<<tot<<endl;
	return 0;
}

Pascal :

var
  l,r:1..10000;
  i,j,h,c:longint;
  s:string;
begin
  {assign(input,'two.in');
  assign(output,'two.out');
  reset(input);
  rewrite(output);}
  readln(l,r);
  c:=0;
  for i:=l to r do
    begin
      str(i,s);
      h:=length(s);
      for j:=1 to h do
        if s[j]='2'
          then c:=c+1;
    end;
  writeln(c);
 { close(input);
  close(output);}
end.

Java :

import java.util.Scanner;


public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while(sc.hasNextLine()){
			String s = sc.nextLine();
			String[] ss = s.split(" ");
			if(ss.length!=2){
				return;
			}
			int a = Integer.parseInt(ss[0]);
			int b = Integer.parseInt(ss[1]);
			int count1 = getCount(a),count2 = getCount(b);
			
			while(a!=0){
				int t = a%10;
				if(t==2){
					count1 --;
				}
				a = a/10;
			}
			System.out.println(count2-count1);
			
		}
		
		
		
	}

	public static int getCount(int n){
		int count = 0;
		int k = 1;
		while(k<=n){
			int after = n%k;
			int before  = n/10/k;
			int cur = n/k%10;
			
			if(cur>2){
				count = count+ (before+1)*k;
			}else if(cur<2){
				count = count + before*k;
			}else if (cur==2){
				count = count + before*k+after+1;
			}
			k*=10;

			
		}
		
		
		
		return count;
	}
}