View Compilation Error

0_0_37973500_9802.cpp: In function 'int find_max(int, int)':
0_0_37973500_9802.cpp:29:3: error: 'ans' was not declared in this scope
   ans=max(ans,a[end]);
   ^
0_0_37973500_9802.cpp:37:9: error: 'ans' was not declared in this scope
  return ans;
         ^