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

#define MIN(A, B) ((A < B) ? (A) : (B))

/* -------- INPUT WITH PUSHBACK */
int _getchar()
{
    extern int buffi;
    extern char buffer[];
    return buffi ? buffer[--buffi] : getchar();
}
#undef getchar
#define getchar() _getchar()


/* --------- MAIN PROGRAM */
#define SLEN 10
void ungets(char *s);

/* this program copies its input to its output,
 * if ungets wokrks as expected */
int main()
{
    int i, c;
    char s[SLEN+1];

    for (i = 0; i < SLEN && (c = getchar()) != EOF; i++)
        s[i] = c;
    s[i] = '\0';

    ungets(s);
    while ((c = getchar()) != EOF)
        putchar(c);
}


#define BUFF_SIZE 100 
int buffi;
char buffer[BUFF_SIZE];

/* ungets: pushes string s back to input */
void ungets(char *s)
{
    int i = strlen(s);
    for (i = MIN(i, BUFF_SIZE-buffi)-1; i >= 0; i--, buffi++)
        buffer[buffi] = s[i];
}