Hello all


We have a column (A) like this:

BTCUSDT
BCCUSDT
ETHUSDT
LTCUSDT
BCCBNB
NEOUSDT
QTUMUSDT
BNBUSDT
LTCBNB
NEOBNB
REPBNB
XZCBNB
BCCETH
QTUMBNB
WTCBNB
NEBLBNB
LSKBNB
MCOBNB
XRPUSDT
ONTBNB
DASHETH
WANBNB
ZECETH
WAVESBNB
NANOBNB
PIVXBNB
VENBNB
NULSBNB
AEBNB
ICXBNB
XMRETH
DGDETH
ADAUSDT
STEEMBNB
AIONBNB
LTCETH
RLCBNB
VIABNB
IOTABNB
BCCBTC
RDNBNB
NAVBNB
TRIGBNB
NEOETH
ETHBTC
etc


These are currency symbols in ratio format.
Both the symbol and the base currency can have different character length.

We want to extract the symbols only, separated from the base.
The current possible bases (last letters) are:

BNB
USDT
ETH
BTC

so as an example:
BTCUSDT => BTC
WAVESBNB => WAVES
ETHBTC => ETH


How do we do it?