C++ :

#include<bits/stdc++.h>
using namespace std;
long long a;
int main()
{
	cin>>a;
	cout<<abs(a);
	
	return 0;
}

Pascal :

var n:longint;
begin
 readln(n);
 writeln(abs(n));
end.

Java :

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner cin = new Scanner(System.in);
    while (cin.hasNext()) {
      int a = cin.nextInt();
      if(a>=0){
          System.out.println(a);
      }else{
          System.out.println(-a);
    }
  }
}
}