With reference to ancient India (600-322 BC), consider the following pairs:
1. Territorial region: Asmaka, River flowing in the region: Godavari
2. Territorial region: Kamboja, River flowing in the region: Vipas
3. Territorial region: Avanti, River flowing in the region: Mahanadi
4. Territorial region: Kosala, River flowing in the region: Sarayu
How many of the pairs given above are correctly matched?