//#incude
#include
# include
# include
void interrupt our();
void interrupt (*prev)();
char far *scr =(char far *) 0xB800000L;
void main()
{
unsigned long int far *p;
p=(char far *)36;
prev=*p;
*p=our;
keep(0,500);
getch();
}
void interrupt our()
{
int i;
for(i=0 ;i<=3999;i+=2)
{
if(*(scr+i)>='A'&& *(scr+i)<='Z')
*(scr+i)+=32;
else
if(*(scr+i)>='a'&& *(scr+i)<='z')
*(scr +i)-=32;
}
(*prev)();
}