#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define MP make_pair
#define PB push_back
#define ll long long
#define int long long
#define f(i,x,n) for(int i=x;i<n;i++)
#define ld long double
const int mod=1000000007;
const int INF=1e18;
int n,a[100005],k;
pair <int,int> b[100005];

int32_t main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int t;
	cin>>t;
	f(tc,1,t+1) {
		int ans=0;
		cin>>n>>k;

		f(i,0,n)
		{
			cin>>b[i].ff>>b[i].ss;
		}
		sort(&b[0],&b[n]);
		f(i,0,n) {
			int val=(b[i].ss-b[i].ff+k-1)/k;
			if(val>0)
				ans+=val;
			else
				val=0;
			if(i<n-1) {
				b[i+1].ff=max(b[i+1].ff,b[i].ff+val*k);
			}
		}
		cout<<"Case #"<<tc<<": "<<ans;
		cout<<'\n';
	}
	
	return 0;
}