ConcatPath.cs

static void PrepararTerreno() => Directory.CreateDirectory($"C:/Users/{Environment.UserName}/Documents/Cadastro");

static void PrepararTerreno() => Directory.CreateDirectory($@"C:\Users\{Environment.UserName}\Documents\Cadastro");

static void PrepararTerreno() => Directory.CreateDirectory($"C:\\Users\\{Environment.UserName}\\Documents\\Cadastro");

//https://pt.stackoverflow.com/q/445467/101