View Compilation Error

0_0_30473390_15547.cpp: In function 'll solve(int)':
0_0_30473390_15547.cpp:36:36: error: 'mod' was not declared in this scope
         ans=(ans-1LL*(j-i+1)*(j+i)%mod*inv2%mod*S(n/i))%mod;
                                    ^
0_0_30473390_15547.cpp:36:40: error: 'inv2' was not declared in this scope
         ans=(ans-1LL*(j-i+1)*(j+i)%mod*inv2%mod*S(n/i))%mod;
                                        ^
0_0_30473390_15547.cpp:36:54: error: 'S' was not declared in this scope
         ans=(ans-1LL*(j-i+1)*(j+i)%mod*inv2%mod*S(n/i))%mod;
                                                      ^