#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void reverse(char *s) {
  int i, j;
  char t;

  for (i=0, j=strlen(s); i < j; i++, j--) {
    t = s[i];
    s[i] = s[j-1];
    s[j-1] = t;
  }

  s[strlen(s)] = '\0';
}

int main(int argc, char *argv[]) {
  char *buffer = malloc(1024);

  strcpy(buffer, argv[1]);

  reverse(buffer);

  printf("%s\n", buffer);
  return 0;
}