#include<stdio.h>
#include<stdlib.h>
int main(void)
{
    int n;
    for( n = 1 ; n <= 15 ; n++ )
    {
        char cmd[100];
        sprintf(cmd,"ren %d.in .%d.in",n,n);
        system(cmd);
        sprintf(cmd,"ren %d.out .%d.out",n,n);
        system(cmd);
    }
}