answer.code:3:7: error: expected nested-name-specifier before ‘ll’
    3 | using ll = long long;
      |       ^~
answer.code: In function ‘int main()’:
answer.code:5:5: error: ‘ll’ was not declared in this scope
    5 |     ll a=1e6,b=1e9+7;
      |     ^~
answer.code:6:14: error: template argument 2 is invalid
    6 |     vector<ll> v(31,-1),w(31,-1);
      |              ^
answer.code:6:23: error: expression list treated as compound expression in initializer [-fpermissive]
    6 |     vector<ll> v(31,-1),w(31,-1);
      |                       ^
answer.code:6:32: error: expression list treated as compound expression in initializer [-fpermissive]
    6 |     vector<ll> v(31,-1),w(31,-1);
      |                                ^
answer.code:7:6: error: invalid types ‘int[int]’ for array subscript
    7 |     v[0]=1;
      |      ^
answer.code:8:6: error: invalid types ‘int[int]’ for array subscript
    8 |     v[1]=0;
      |      ^
answer.code:9:6: error: invalid types ‘int[int]’ for array subscript
    9 |     w[0]=0;
      |      ^
answer.code:10:6: error: invalid types ‘int[int]’ for array subscript
   10 |     w[1]=1;
      |      ^
answer.code:11:11: error: expected ‘;’ before ‘i’
   11 |     for(ll i=2;i<31;i++){
      |           ^~
      |           ;
answer.code:11:16: error: ‘i’ was not declared in this scope
   11 |     for(ll i=2;i<31;i++){
      |                ^
answer.code:12:32: error: ‘b’ was not declared in this scope
   12 |         v[i]=(v[i-2]+2*w[i-1])%b;
      |                                ^
answer.code:15:7: error: expected ‘;’ before ‘d’
   15 |     ll d,e;
      |       ^~
      |       ;
answer.code:16:10: error: ‘d’ was not declared in this scope
   16 |     cin>>d;
      |          ^