using System.Net.Http;
using System.Collections.Generic;
using System.Threading.Tasks;
using System;

class Program {
    static async Task Main() {
        var client = new HttpClient();
        client.DefaultRequestHeaders.Add("Authorization", "Bearer YOUR_API_TOKEN");

        // Create
        var form = new FormUrlEncodedContent(new Dictionary<string,string> {
            ["content"] = "Hello from C#",
            ["type"] = "public",
            ["expiration"] = "unlimited",
            ["paste_title"] = "CSharp Test"
        });
        var create = await client.PostAsync("https://paste.su/dev", form);
        var created = await create.Content.ReadAsStringAsync();
        Console.WriteLine("Create: " + created);

        // Fetch
        // replace PASTE_ID with parsed id from 'created'
        var get = await client.GetAsync("https://paste.su/dev?paste_id=PASTE_ID");
        Console.WriteLine("Fetch: " + await get.Content.ReadAsStringAsync());
    }
}