/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
import java.text.SimpleDateFormat;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String dt = "1970-12-31";  // Start date
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		Calendar c = Calendar.getInstance();
		c.setTime(sdf.parse(dt));
		c.add(Calendar.DATE, 1);  // number of days to add
		dt = sdf.format(c.getTime());  // dt is now the new date
		System.out.println(dt);
	}
}