message: it is INDEX not COIN
diff: @@ -82,9 +82,9 @@ impl<Addressing: Clone> InputSelectionAlgorithm<Addressing> for Blackjack<Addres
  {
  use tx::{TxId, TxInWitness};
  - const MAX_OVERHEAD_COIN : usize = 10; // 64bytes + 2 bytes of CBOR...
  + const MAX_OVERHEAD_INDEX : usize = 5; // 32bits + 1 bytes of CBOR...
  const MAX_OVERHEAD_TXID : usize = TxId::HASH_SIZE + 2; // 2 bytes of Cbor...
  - const MAX_OVERHEAD_TXIN : usize = MAX_OVERHEAD_COIN + MAX_OVERHEAD_TXID + 1; // 2 bytes of cbor
  + const MAX_OVERHEAD_TXIN : usize = MAX_OVERHEAD_INDEX + MAX_OVERHEAD_TXID + 2; // 2 bytes of cbor
  let signature_cost = fee_algorithm.estimate_overhead(cbor!(TxInWitness::fake()).unwrap().len())?
  .unwrap_or(Fee::new(Coin::zero())).to_coin();
  