import java.util.*;
import java.lang.*;

public class RemoveAdjacent {
    public static void main(String[] args) {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        String s = "geeksforgeeks";
        removeDuplicate(s, 0);
    }

    public static void removeDuplicate(String d, int i) {
        int n = d.length();
        if (d.charAt(i) == d.charAt(i + 1) && i <= n) {
            d = d.substring(0, i) + d.substring(i + 1, n + 1);
            i = i + 1;
            removeDuplicate(d, i);
        } else if (i <= n) {
            i = i + 1;
            removeDuplicate(d, i);
        } else {
            System.out.println(d);
            return;
        }
    }
}

at java.lang.String.substring(String.java:1963)
String.java:1963
    at RemoveAdjacent.removeDuplicate(RemoveAdjacent.java:16)
RemoveAdjacent.java:16
    at RemoveAdjacent.removeDuplicate(RemoveAdjacent.java:21)
RemoveAdjacent.java:21
    at RemoveAdjacent.main(RemoveAdjacent.java:10)