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

struct Data
{
    int16_t x;
    int64_t y;
};

int
main (int argc,char **argv)
{
    enum { MAX_BUF = 10 };
    int buf1[MAX_BUF], buf2[MAX_BUF];
    int f, count = 0, i = 1;
    struct Data *str;
    f = open(argv[1],O_RDWR)
    while(read(f, &str.x, 2) != 0 && read(f, &str.y, 8) != 0) {
        str.y += str.x * argv[2];
        ++count;
    }
    lseek(f, count*MAX_BUF, 2);
    while(i <= count/2) {
        read(f, buf1, MAX_BUF);
        lseek(f, i*MAX_BUF, 2);
        read(f, buf2, MAX_BUF);
        lseek(f, i*MAX_BUF, 2);
        write(f, buf1, MAX_BUF);
        lseek(f, i*MAX_BUF, 0);
        write(f, buf2, MAX_BUF);
        ++i;
    }
    close(f);
    return 0;
}