#define N 21
#include <stdio.h>
#include <string.h>
#include <ctype.h>
char d[N];
int length;
void Permutation(char s[], int i);
void Sort(char s[]);
int count = 0;
void main()
{
char s[N],ss[N];
int flag ;
do
{
printf("Please input less than 20 characters. \n");
gets(s);
flag = 0;
strcpy(ss,"\0");
int ilength = strlen(s);
if (ilength < 5)
flag = 1;
for (int icount = 0; icount < 5; icount++)
{
if(!isalpha(s[icount]))
flag = 1;
}
strcpy(ss,s);
}
while (flag == 1);
//Sort(ss);
printf("How many characters do you want to permute: \n");
printf("Enter a number : ");
scanf("%d", &length);