POJ 3286 How many 0's?

#include <set>
#include <map>
#include <queue>
#include <math.h>
#include <vector>
#include <string>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <algorithm>

#define eps 1e-8
#define pi acos(-1.0)
#define inf 107374182
#define inf64 1152921504606846976
#define lc l,m,tr<<1
#define rc m + 1,r,tr<<1|1
#define iabs(x)  ((x) > 0 ?

(x) : -(x))
#define clear1(A, X, SIZE) memset(A, X, sizeof(A[0]) * (SIZE))
#define clearall(A, X) memset(A, X, sizeof(A))
#define memcopy1(A , X, SIZE) memcpy(A , X ,sizeof(X[0])*(SIZE))
#define memcopyall(A, X) memcpy(A , X ,sizeof(X))
#define max( x, y )  ( ((x) > (y)) ? (x) : (y) )
#define min( x, y )  ( ((x) < (y)) ? (x) : (y) )

using namespace std;

long long does(long long num)
{
if(num<0)return 0;
long long ans=1,div=10;
while(num/div)
{
if((num%div-num%(div/10))==0)ans+=((num/div)-1)*(div/10)+(num%(div/10))+1;
else ans+=(num/div)*(div/10);
div*=10;
}
return ans;
}

int main()
{
long long n,m;
while(scanf("%lld%lld",&m,&n),n!=-1&&m!=-1)
{
printf("%lld\n",does(n)-does(m-1));
}
return 0;
}