class Solution {
public:
bool isPalindrome(int x) {
if(x < 0) return false;
int a1 = 1;
while(a1<=x/10)a1*=10;
while(x > 0){
if(x/a1!=x%10)return false;
x-=x/a1*a1;
x/=10;
a1/=100;
}
return true;
}
};