View Compilation Error

0_0_23369733_12452.cpp: In function 'int main()':
0_0_23369733_12452.cpp:15:17: error: 'mem' was not declared in this scope
         mem(dp,0);  
                 ^
0_0_23369733_12452.cpp:25:48: error: 'max' was not declared in this scope
                 dp[j]=max(dp[j],dp[j-w[i]]+c[i]);  
                                                ^