FIND THE Nth TERM IN THE SERIES

Find the Nth term in d series that contains only 3 & 7

eg, 3,7,33,37,73,77,333,337,373,377,.....

Input Format

A single number N

where 0 < N < 100

Output Format

The number that is in d Nth position in d series.

Sample Input

3

Sample Output

33

Explanation

3,7,33,37,..

where 33 is d 3rd number in d series.

OUTOUT:

#include <stdio.h>

#include <string.h>

#include <math.h>

#include <stdlib.h>

int main() {

 int x;

    scanf("%d",&x);

  int i;

    for(i=0;x>=pow(2,i);i++)

       x=x-pow(2,i);

    char s[i];

    s[i]='\0';

    for(i=i-1;i>=0;i--)

    {

        if(x%2==0)

            s[i]='3';

        else

            s[i]='7';

        if(x!=0)

            x=x>>1;

    }    

  printf("%s",s);

    return 0;

}