def numbers=[1:[1]];


def getNext(number) {
    if((number%2)==0) {
        return number/2;
    } else {
        return 3*number+1;
    }
}

def getSequence(numbers, number) {
    if(numbers.containsKey(number)) {
        return numbers.get(number);
    } else {
        def next = getNext(number).toInteger();
        def nextSeq =  getSequence(numbers, next);
        def seq = nextSeq.clone();
        seq.add(0, number);
        numbers[number]=seq;
        return seq;
    }
}

for(i in 1..1000) {
    getSequence(numbers, i);
    if(i%100000==0) {
        println "$i reached";
    }
}

max = 0;
numbers.each { k, v->
    if(v.size()>max) {
        max = v.size();
    }
}
println max;