public static void Main()
var query = new Span<char>("instanceId=123asdasd&a=v&asd=123&instanceId=123".ToArray());
var instanceId = "instanceId=".ToArray();
for(var i = 0; i < query.Length; i++)
if(query[i]== instanceId[expected])
query[total] = instanceId[expected];
if(expected == instanceId.Length)
total = total - expected;
Console.WriteLine(query[..total].ToString());