swap First Digit with Last Digit

#include <iostream>
#include <math.h>
using namespace std;

int main()
{
    int n, first, last, sum, digits, nn, a, b;
    cout << "\n\n Find the number after swapping the first and last digits:\n";
    cout << "-------------------------------------------------------------\n";
    cout << " Input any number: ";
    cin >> n;
    if (n % 2 == 0) {
        digits = log10(n);
        first = n / pow(10, digits);
        last = n % 10;
        a = first * (pow(10, digits));
        b = n % a;
        n = b / 10;
        nn = last * (pow(10, digits)) + (n * 10 + first);
        cout << " The number after swaping the first and last digits are: " << nn << endl;
    }

    system("pause");
}