In Santa's toy factory, the elves are developing a programming language called Santa.js 👨‍💻👩‍💻 based on symbols to control their toy machines 🚂.

They have created a simple instruction system and need your help to build a compiler that interprets these symbols.

The compiler works with a counter that initially has a value of 0. The instructions will modify the value of this counter.

Elves' language instructions based on symbols:

• +: Increments the counter value by 1.
• *: Multiplies the counter value by 2.
• -: Subtracts 1 from the counter value.
• %: Mark a return point. Does not modify the counter.
• <: Go back once to the last instruction with the % symbol it has seen. If there is no previous %, it does nothing.
• ¿: Starts a conditional block that executes if the counter is greater than 0.
• ?: Ends a conditional block.

Create a compile function that receives a string with the language instructions and returns the result of executing them. Here are some examples:

compile('++*-') // 3
// (1 + 1) * 2 - 1 = 3

compile('++%++<') // 6
// 1 + 1 + 1 + 1 + 1 + 1 = 6

compile('++<--') // 0
// 1 + 1 - 1 - 1 = 0

compile('++¿+?') // 3
// 1 + 1 + 1 = 3

compile('--¿+++?') // -2
// - 1 - 1 = -2