/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
    static int indexOf(String str, String sub) {
        if (str.length() < sub.length()) return -1;
        if (str.startsWith(sub)) return 0;
        int res = indexOf(str.substring(1), sub);
        return res < 0 ? res : 1+res;
    }
	public static void main (String[] args) throws java.lang.Exception
	{
		System.out.println(indexOf("Barak Obama", "Obama"));
		System.out.println(indexOf("Barak Obama", "Osama"));
	}
}

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