View Compilation Error

0_0_36670003_2943.cpp: In function 'int main()':
0_0_36670003_2943.cpp:43:13: error: 'vi' was not declared in this scope
             vi[a] = 1,vi[b] = 1;
             ^
0_0_36670003_2943.cpp:82:54: error: 'vi' was not declared in this scope
                 for(int i = 0;i <= N;i ++ ) f[i] = i,vi[i] = 0;
                                                      ^