View Compilation Error

0_0_29779985_15995.cpp: In function 'int main()':
0_0_29779985_15995.cpp:45:51: error: 'a' was not declared in this scope
         for (ll i = 0; i < n; i++) scanf("%lld", &a[i]);
                                                   ^
0_0_29779985_15995.cpp:51:47: error: 'a' was not declared in this scope
                     loops[loop_num].push_back(a[j]);
                                               ^