How can I make Java recognize "yes"

import java.util.Scanner;
public class Quest {
public static void main(String[] args){
	
	Scanner ui = new Scanner(System.in);
	int a=1,b=2;
	System.out.println("You have come across a troll! Do you kill it? Press 1 to fight the troll");
	a=ui.nextInt();
	if(a==1){
		System.out.println("You have killed it!");
		
	}
	
	else
		System.out.println("you lost");
	
	
	
	
	
	
	
	
}
}