View Compilation Error

0_0_39648912_24966.cpp: In function 'long long int gets(long long int, long long int)':
0_0_39648912_24966.cpp:21:45: error: 'mod2' was not declared in this scope; did you mean 'modf'?
   21 |         return ((hs2[r]-hs2[l-1]*p2[r-l+1])%mod2+mod2)%mod2;
      |                                             ^~~~
      |                                             modf