View Compilation Error

0_0_39778847_25708.cpp:5:8: error: 'MAXN' was not declared in this scope
    5 | ULL fn[MAXN+1];
      |        ^~~~
0_0_39778847_25708.cpp: In function 'void setfn()':
0_0_39778847_25708.cpp:11:5: error: 'fn' was not declared in this scope
   11 |     fn[0] = 0;
      |     ^~
0_0_39778847_25708.cpp:14:17: error: 'MAXN' was not declared in this scope
   14 |     for(i=3; i<=MAXN; i++)
      |                 ^~~~
0_0_39778847_25708.cpp: In function 'int main()':
0_0_39778847_25708.cpp:26:26: error: 'fn' was not declared in this scope; did you mean 'n'?
   26 |         printf("%lld\n", fn[n]);
      |                          ^~
      |                          n