View Compilation Error

0_0_16156781_5683.cpp:5:1: error: 'LL' does not name a type
 LL euler_phi(int n){
 ^
0_0_16156781_5683.cpp: In function 'int main()':
0_0_16156781_5683.cpp:25:23: error: 'sqrt' was not declared in this scope
    double s = sqrt( n );
                       ^
0_0_16156781_5683.cpp:28:41: error: 'euler_phi' was not declared in this scope
      if( i!=n/i ) ans = (ans+euler_phi(i)*euler_phi(n/i)*2)%mod;
                                         ^
0_0_16156781_5683.cpp:29:34: error: 'euler_ph' was not declared in this scope
      else ans = (ans+p(euler_ph(i)))%mod;
                                  ^