Codes for converting a digit to Strings

#include"stdio.h"

#include"conio.h"

void main()

{

char a[10][10]={"ONE","TWO","THREE","FOUR","FIVE","SIX",

        "SEVEN","EIGHT","NINE","TEN"};

char b[10][10]={"ELEVEN","TWELVE","THIRTEEN","FOURTEEN",

        "FIFTEEN","SIXTEEN","SEVENTEEN","EIGHTTEEN",

        "NINETEEN"};

char c[10][10]={"TEN","TWENTY","THIRTY","FOURTY","FIFTY","SIXTY",

        "SEVENTY","EIGHTY","NINTY","HUNDRED"};

long r,s,t,n;

clrscr();

printf("----------INPUT A NUMBER BELOW 1 CRORE----------\n\n");

scanf("%ld",&n);

while (n>=10000000)

       {

       printf ("\nERROR: Invalid Input!\n");

       printf ("\nEnter the number again:");

       scanf ("%ld",&n);

       }

if(n>=10000000)

    printf("INVALID INPUT !!!");

if(n==0)

    printf("ZERO");

printf("\n\n\n");

if(n>999999)

    {

    r=n/100000;

    if(r>10&&r<20)

        {

        r=r%10;

        printf("%s LAKH ",b[r-1]);

        }

    else

        {

        s=r/10;

        t=r%10;

        printf("%s ",c[s-1]);

        printf("%s LAKH ",a[t-1]);

        }

    n=n%100000;

    }

if(n>=100000)

    {

    r=n/100000;

    printf("%s LAKH ",a[r-1]);

    n=n%100000;

    }

if(n>9999)

    {

    r=n/1000;

    if(r>10&&r<20)

        {

        r=r%10;

        printf("%s THOUSAND ",b[r-1]);

        }

    else

        {

        s=r/10;

        t=r%10;

        printf("%s ",c[s-1]);

        printf("%s THOUSAND ",a[t-1]);

        }

    n=n%1000;

    }

if(n>=1000)

    {

    r=n/1000;

    printf("%s THOUSAND ",a[r-1]);

    n=n%1000;

    }

if(n>100)

    {

    r=n/100;

    printf("%s HUNDRED ",a[r-1]);

    n=n%100;

    }

if(n>10&&n<20)

    {

    r=n%10;

    printf("%s ",b[r-1]);

    }

if(n>19&&n<=100)

    {

    r=n/10;

    printf("%s ",c[r-1]);

    n=n%10;

    }

if(n>0&&n<=10)

    {

    printf("%s ",a[n-1]);

    }

getch();

}