View Compilation Error

0_0_30509719_24016.cpp: In function 'int main()':
0_0_30509719_24016.cpp:41:15: error: 'mod' was not declared in this scope
         f[i]%=mod;
               ^
0_0_30509719_24016.cpp:45:3: error: 'else' without a previous 'if'
   else cout<<f[n%4018]<<endl;
   ^