Page Hopping

#include <bits/stdc++.h>
using namespace std;
#define PB push_back
#define ZERO (1e-10)
#define INF (1<<29)
#define CL(A,I) (memset(A,I,sizeof(A)))
#define DEB printf("DEB!\n");
#define D(X) cout<<"  "<<#X": "<<X<<endl;
#define EQ(A,B) (A+ZERO>B&&A-ZERO<B)
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
#define IN(n) int n;scanf("%d",&n);
#define FOR(i, m, n) for (int i(m); i < n; i++)
#define REP(i, n) FOR(i, 0, n)
#define F(n) REP(i, n)
#define FF(n) REP(j, n)
#define FT(m, n) FOR(k, m, n)
#define aa first
#define bb second
void ga(int N,int *A){F(N)scanf("%d",A+i);}
unordered_map<int,int> T;
int C,a,b,g[100][100],cc;
int gt(int a){
    if(T.count(a))return T[a];
    return T[a]=C++;
}
double S;
int main(void){
    while(666){
        T.clear(),C=S=0;
        F(100)FF(100)g[i][j]=i==j?0:INF-1;//init
        while(scanf("%d%d",&a,&b),a|b)g[gt(a)][gt(b)]=1;
        if(!C)return 0;
        FT(0,C)F(C)FF(C)g[i][j]=min(g[i][j],g[i][k]+g[k][j]);//FW
        F(C)FF(C)S+=g[i][j];
        printf("Case %d: average length between pages = %.3lf clicks\n",++cc,S/(C*C-C));
    }
}