#include<stdio.h> 
#include<string.h>
 
void calculate(char *a, int i, int n); 
void swap (char *x, char *y); 
int m = 0;
 
int main(){
 
char str[10] = "IoT"; 
int len=0,i=0; len = strlen(str);
 calculate(str, 0, len-1); printf("%d\n",m);
}
 
void swap (char *x, char *y) {
 
char temp;
 
temp =*x;
 
*x=*y;
*y = temp;
}
 
void calculate(char *a, int i, int n) {
 
int j =0; 
if (i == n){
 
m++ ;
}
else{
 
for (j=i; j<=n; j++){ 
swap((a+i), (a+j));
calculate(a, i+1, n);
 
swap((a+i), (a+j));
}}}

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