View Compilation Error

0_0_36602324_26949.cpp: In function 'void solve()':
0_0_36602324_26949.cpp:38:47: error: 'a1' was not declared in this scope
     for (int i = 0; i <= n; i++) scanf("%d", &a1[i]);
                                               ^
0_0_36602324_26949.cpp:45:19: error: 'a1' was not declared in this scope
     int f0 = work(a1, len, Max);
                   ^