Untitled

import std.stdio;
import std.array;
import std.conv;

class Stack
{
    private char[] crates;

    void bottomadd(char crate){
        this.crates ~= crate;
    }

    void topadd(char crate){
        char[] nc = [crate];
        this.crates = nc ~= crates;
    }

    void topadd(char[] cs){
        char[] nc = cs[];
        this.crates = nc ~= crates;
    }

    char consult(){
        return crates[0];
    }

    char[] consultn(int n){
        return crates[0..n];
    }

    char pop(){
        char crate = consult();
        crates = crates[1..$];
        return crate;
    }

    char[] popn(int n){
        char[] crate = consultn(n);
        crates = crates[n..$];
        return crate;
    }

    void print(){
        foreach (c; crates){
            write(c);
            write(" ");
        }
        writeln();
    }

}

class Stacks{

    private Stack[] stacks;

    this(int s){
        stacks = new Stack[s];
        foreach(i; 0 .. s){
            stacks[i] = new Stack();
        }
    }

    void parse(string line){
        for(int i=0; i<9; i++){
            char crate_val = line[(i*4)+1];
            if(crate_val != ' ' && crate_val > '9'){
                assert (crate_val >= 'A' && crate_val <= 'Z');
                stacks[i].bottomadd(crate_val);
            }
        }
    }

    void execute(string command){
        auto split = command.split(" ");
        int amount = to!(int)(split[1]);
        int source = to!(int)(split[3]);
        int destination = to!(int)(split[5]);
        stacks[destination-1].topadd(stacks[source-1].popn(amount));
    }

    char[] get_top_crates(){
        char[] top;
        foreach(stack; stacks){
            top ~= stack.consult();
        }
        return top;
    }

    void print(){
        foreach(s; stacks){
            s.print();
        }
    }
}


void main()
{
    File input = File("../input5", "r");
    string line;
    bool crate_section = true;
    Stacks stacks = new Stacks(9);

    while ((line = input.readln()) !is null){
        line = line.replace("\n", "");
        if (line == ""){
            crate_section = false;
            stacks.print();
            continue;
        }
        if(crate_section){
            stacks.parse(line);
        }else{
            writefln(line);
            stacks.execute(line);
            stacks.print();
            writeln();
        }

    }
    writeln(stacks.get_top_crates());
}