/in/foo.cc: In function 'int main()':
/in/foo.cc:27:38: error: 'j' was not declared in this scope
     if(i&1)ans=(ans-1ll*inv[i]*inv[k-j-1]%mod*(ksm(k-j,n-1)+1ll*ksm(k-j,n-2)*(n-1)%mod)%mod)%mod;
                                      ^
/in/foo.cc:28:36: error: 'j' was not declared in this scope
     else ans=(ans+1ll*inv[i]*inv[k-j-1]%mod*(ksm(k-j,n-1)+1ll*ksm(k-j,n-2)*(n-1)%mod)%mod)%mod;
                                    ^