View Compilation Error

0_0_33793648_18753.cpp:21:1: error: expected unqualified-id before '/' token
 / inv(ll a) { ll p = mod - 2; ll ans = 1; while (p > 0) { if (p & 1)ans = ans * a % mod; a = (a * a) % mod; p >>= 1; }return ans; }
 ^