View Compilation Error

0_0_28144865_15271.cpp: In function 'void solve()':
0_0_28144865_15271.cpp:36:20: error: 'f' was not declared in this scope
     Dirichlet(ans, f);
                    ^
0_0_28144865_15271.cpp: In function 'int main()':
0_0_28144865_15271.cpp:47:20: error: 'f' was not declared in this scope
             cin >> f[i];
                    ^