//1
            if(a%3 == 0 && dp[a/3] == 0){
                qu.add(a/3);
                dp[a/3] = dp[a] + 1;
            }
            //2 
            if(a%2 == 0 && dp[a/2] == 0){
                qu.add(a/2);
                dp[a/2] = dp[a] + 1;
            }
            
            //3
            if(dp[a-1] == 0) {
	            qu.add(a-1);
	            dp[a-1] = dp[a] + 1;
            }