I am trying to get public key from private key using secp256k1 library. https://github.com/bitcoin-core/secp256k1
I set same private key(sk) in here. https://github.com/ethereumbook/ethereumbook/blob/develop/04keys-addresses.asciidoc#ethereum-addresses
unsigned char *sk = "f8f8a2f43c8376ccb0871305060d7b27b0554d2cc72bccf41b2705608452f315";
secp256k1_ec_pubkey_create(secp256k1_ctx, &pk, sk);
secp256k1_ec_pubkey_serialize(secp256k1_ctx, output, &outputlen, &pk, SECP256K1_EC_UNCOMPRESSED);
But serialized public key (output) which I got is
04a82b7752a73ab1de51ae4f614e7e9908fb891c1cdeeab96c0e7c237d3e3a0369daf8eab4e3864668575c5d10fc000a6897b10102c14671140c1cdf9765fd46b0
Not same public key in ethereum book. Am I writing wrong code to get correct public key ?