View Compilation Error

0_0_30459185_9160.cpp:4:7: error: 'esp' does not name a type
 const esp = 1e-6 ;
       ^
0_0_30459185_9160.cpp: In function 'int main()':
0_0_30459185_9160.cpp:28:25: error: 'esp' was not declared in this scope
         if(maxn - ans <=esp)
                         ^