Check palindrome no

#1

why getting error, even I specified all return statements.

#2

please share the correct link.

#3 


#include<iostream>
using namespace std;
int main()
{
    int n,sum=0;
    cin>>n;
    while(n>0)
    {
        int last_digit=n%10;
        sum=sum+last_digit;
        sum*=10;
        n/=10;
    }
    sum/=10;
    cout<<sum;
}