I have this working code:

```
using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;

public class Example {
    public static void Main(string[] args) {
        var files = new Dictionary<string, Dictionary<string, int>>()
                   { { "file1", new Dictionary<string, int>() { { "A", 1 } } } };
        foreach(var file in files) {
            File.WriteAllLines(file.Key + ".txt", file.Value.Select(
                    item => item.Key + item.Value.ToString("000")).ToArray());
        }
    }
}

```

But I want to change the `foreach` to LINQ syntax. Nothing I already tried worked.