View Compilation Error

0_0_35587297_11896.cpp: In function 'void fb()':
0_0_35587297_11896.cpp:6:2: error: 'f' was not declared in this scope
  f[0] = 7;
  ^
0_0_35587297_11896.cpp: In function 'int main()':
0_0_35587297_11896.cpp:17:6: error: 'f' was not declared in this scope
   if(f[n] % 4 == 2)
      ^