// A Program to check whether a number is divisible by 7

#include <stdio.h>

 

int isDivisibleBy7( int num )

{

    // If number is negative, make it positive

    if( num < 0 )

        return isDivisibleBy7( -num );

 

    // Base cases

    if( num == 0 || num == 7 )

        return 1;

    if( num < 10 )

        return 0;

 

    // Recur for ( num / 10 - 2 * num % 10 )

    return isDivisibleBy7( num / 10 - 2 * ( num - num / 10 * 10 ) );

}

 

// Driver program to test above function

int main()

{

    int num = 616;

    if( isDivisibleBy7(num ) )

        printf( "Divisible" );

    else

        printf( "Not Divisible" );

    return 0;

}