UVA - 12517 - Digit Sum (C solution)

#include <stdio.h>

long sumofDigit(long n, long ditInd, long poss) {
        if (n == 0) {
            return 0;
        }
        long m = n % 10;
        return n / 10 * 45 * ditInd + m * poss + m * (m - 1) / 2 * ditInd + sumofDigit(n / 10, ditInd * 10, poss + m * ditInd);
}
int main()
{
    long x,y;
    while(1){
        scanf("%ld %ld",&x,&y);
        if(x==0 &&y==0)
            break;
        printf("%ld\n",sumofDigit(y,1,1)-sumofDigit(x-1,1,1));
    }
    return 0;
}