// https://qoj.ac/contest/1867/problem/9075
/*
 * ===============================
 * @Author: feng_Lrefrain
 * @DateTime: 2024-12-22 15:31:43 CST(UTC+8)
 * ===============================
 */
#include <bits/stdc++.h>
#define int long long
#define vi vector<int>
#define pii pair<int,int>
#define fi first
#define se second
#define pb push_back
#define rep(I,S,N) for(int I=(S);I<(N);++I)
#define per(I,S,N) for(int I=(N)-1;I>=(S);--I)
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
using namespace std;
typedef long long ll;
typedef double db;
// int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};
// inline ll gcd(ll a,ll b) {return b?gcd(b,a%b):a;}
// inline ll lcm(ll a,ll b) {return a/gcd(a,b)*b;}
// inline ll ksm(ll a,ll b,ll p) {ll ans=1;while(b){if(b&1)ans=(ans*a)%p;b>>=1;a=(a*a)%p;}return ans%p;}
// inline ll lowbit(int x) {return x&(-x);}
const int N = 2e5 + 10;
const int M = 998244353, MM = 1e9 + 7, inf = 1e18;

int solve() {
	int a, b; cin >> a >> b;
	vi aa[2], bb[2];
	rep(i, 0, 62) if (a >> i & 1) aa[i & 1].pb(i);
	rep(i, 0, 62) if (b >> i & 1) bb[i & 1].pb(i);
	if (SZ(aa[0]) != SZ(bb[0]) || SZ(aa[1]) != SZ(bb[1])) {
		// cout << "-1\n";
		return -1;
	}
	int ans = 0;
	rep(i, 0, SZ(aa[0])) ans += abs(aa[0][i] - bb[0][i]);
	rep(i, 0, SZ(aa[1])) ans += abs(aa[1][i] - bb[1][i]);
	// cout << (ans >> 2) << '\n';
	return ans / 2;
}
/*


*/
signed main() {
	cin.tie(nullptr)->sync_with_stdio(false);
	// cout << fixed << setprecision(6);
	int _ = 1;
	cin >> _;
	rep(i, 1, _ + 1) cout << "Case " << i << ": " << solve() << '\n';
	return 0;
}