#include <iostream>
using namespace std;
int main()
{
int result=0;
int n1, n2, n3, n4, n5, n6;//906609===> n1=9
for(int i =999;i>=99;i--)
{
   for(int j=999;j>=99999/i+1;j--)
   {
       n1=i*j/100000;
       n2=i*j/10000-10*n1;
       n3=i*j/1000-10*n2-100*n1;
       n4=i*j%1000/100;
       n5=i*j%100/10;
       n6=i*j%10;
       if(n1==n6 && n2==n5 && n3==n4 && i*j>result) result=i*j;
    }
}
    cout<<result;
    return 0;
}