Gemini 3 Pro Preview Pricing: How are the higher prices for Gemini 3 tokens calculated?

If a prompt exceeds 200,000 tokens, is the higher price (e.g. $4 per 1M input tokens) applied only to the tokens above 200,000, or does the entire prompt immediately get billed at the higher per-million-token rate once the threshold is crossed?

https://ai.google.dev/gemini-api/docs/pricing