View Compilation Error

0_0_39229482_15535.cpp: In function 'int main()':
0_0_39229482_15535.cpp:30:37: error: 'cnt' was not declared in this scope; did you mean 'int'?
   30 |                 cout << "Case #" << cnt << ": " << solve(r,k)-solve(l-1,k) << "\n" ;
      |                                     ^~~
      |                                     int