lightoj - 1136 - Division By 3

#include<bits/stdc++.h>
using namespace std;
#define fast()(ios_base::sync_with_stdio(false),cin.tie(NULL));
typedef long long ll;
int main()
{
    ll test;
    cin>>test;
    for(ll t=1;t<=test;t++)
    {
        ll a,b,c,d,e,f;
        cin>>a>>b;
        c=a/3;
        if(a%3!=0)c++;
        d=b/3;
        if(b%3!=0)d++;
        e=(d-c)*2+2;
        if(a%3==0)e--;
        if(b%3==1)e-=2;
        if(b%3==2)e--;
        cout<<"Case "<<t<<": "<<e<<endl;

    }
}