View Compilation Error

0_0_21829999_14893.cpp: In function 'void Mobius()':
0_0_21829999_14893.cpp:48:22: error: 'N' was not declared in this scope
     for(int i = 1; i<N; ++i){
                      ^
0_0_21829999_14893.cpp:51:48: error: 'u' was not declared in this scope
         for(int j = k;j < N;j += k)  sum[j] += u[j/k];
                                                ^