#include <stdio.h>
#include <stdlib.h>
int main()
{
    char c;
    char* mas = malloc(sizeof(char));
    char* start = mas;
    while((c = getchar()) != EOF)
    {
        *(mas) = c;
        mas++;
        start = realloc(start,  mas-start);
    }
    printf("\n");
    for(char* it = mas; it >= start; it--)
    {
        printf("%c", *it);
    }
    printf("\n");
    free(start);
    return 0;
}