View Compilation Error

0_0_17329193_28873.cpp: In function 'int main()':
0_0_17329193_28873.cpp:41:25: error: invalid initialization of non-const reference of type 'int&' from an rvalue of type 'int'
             ans=(ans+f(i*dp[n][i]))%mod;
                         ^
0_0_17329193_28873.cpp:16:6: note: in passing argument 1 of 'void f(int&)'
 void f(int &x){
      ^