View Compilation Error

0_0_20875781_18049.cpp: In function 'void BSGS_init(long long int, long long int)':
0_0_20875781_18049.cpp:93:28: error: 'mod_reverse' was not declared in this scope
     inv_aup=mod_reverse(e,m);
                            ^
0_0_20875781_18049.cpp: In function 'int main()':
0_0_20875781_18049.cpp:153:62: error: 'mod_reverse' was not declared in this scope
                 long long cur=(B*mod_reverse(A,(sump[i]-1)/gg))%((sump[i]-1)/gg);
                                                              ^