#include?"stdio.h"
int?main(void){
char?str[21];
int?i;
printf("Enter?a?string(<20?characters)...\nstr=");
for(i=0;i<21;i++)
if((str[i]=getchar())=='\n')
break;
for(printf("rev="),i--;i>=0;printf("%c",str[i--]));
printf("\n");
return?0;
}