What is the shortest LOOP program that outputs 2016?

Question

LOOP

This challenge is based around a modified version of the programming language LOOP.

A program may be of any of the following forms:

• P;Q, where P and Q are subprograms
  • Subprogram P is executed, then subprogram Q is executed.
• x++, where x is a variable
  • Variable names are the letter x followed by a whole number (0, 1, 2, etc.). The value of variable x is incremented and assigned to variable x.
• x:=y, where x and y are variables
  • The value of variable y is assigned to variable x
• LOOP x DO P END, where x is a variable, and P is a subprogram
  • Subprogram P is executed a number of times equal to the value of x at the start of the loop. If the value of x changes during the loop, the number of iterations does not change.

Spaces and newlines may be inserted anywhere.

For this challenge, you may not use constants.

For example, the code
LOOP x1 DO x2 := x2 + 1; LOOP x2 DO x1++ END END
will set x1 to the x1^th triangle number, by adding 1, then 2 etc.

Task

All variables are initialized to 0. The output of the program is the final value of x0, and the length of a program is the total count of increment/decrement/assignment/loop. The goal is to output 2016 with a program that is as short as possible.

Here is an interpreter for the modified language used in this challenge.

Answer 1

Naive attempt, 15 statements

This uses the factorization of 2016 into 2^5*3^2*7.

x1++;
x1++;
x2:=x1;
x2++;
x3:=x2+x2;
x3++;
LOOP x1 DO
LOOP x1 DO
LOOP x1 DO
LOOP x1 DO
LOOP x1 DO
LOOP x2 DO
LOOP x2 DO
LOOP x3 DO
x0++
END
END
END
END
END
END
END
END

I've gotten this to run on the provided interpreter by replacing things like x1++; with x1:=x1+1;, although I did not use "strict mode."