CF 1538 F Interesting Function

#include 
using namespace std;
typedef long long ll;
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        int l,r;
        scanf("%d %d",&l,&r);
        int sum=0;
        while(l!=0 || r!=0)
        {
            sum+=r-l;
            l/=10;
            r/=10;
        }
        printf("%d\n",sum);
    }
    return 0;
}