package My;

public class Example3_9 
{
	public static void main(String args[])
	{	
		double p = 13, r = 0.012;
		int i = 0;
		while(p<=20)
                              {
			p = p * (1 + r);
			i = i + 1;
                              }
		System.out.println(i+"年后，我国人口达到"+p+"亿");
	}
}