jiaming

#include <stdio.h>
#include <math.h>

long fun(long s)
{
    long n = 0, t1;
    long t = 0;
    while (s)
    {
        s /= 10;
        t1 = s % 10;
        s /= 10;
        t += t1 * pow(10, n);
        n++;
    }
    return t;
}
int main(void)
{
    long s;
    scanf("%ld", &s);
    printf("%ld", fun(s));
}