Red Huang

//====================================================================||  
//                                                                    ||  
//                                                                    ||  
//                         作者 : GCA                               ||  
//                  6AE7EE02212D47DAD26C32C0FE829006                  ||  
//====================================================================||  
#include <iostream>  
#include <cstdio>  
#include <cstring>  
#include <algorithm>  
#include <cmath>  
#include <climits>  
#include <vector>  
#include <set>  
#include <map>  
#include <queue>  
#include <cctype>  
#include <utility>  
using namespace std;  
#ifdef ONLINE\_JUDGE  
#define ll "%lld"  
#else  
#define ll "%I64d"  
#endif  
typedef unsigned int uint;  
typedef long long int Int;  
#define Set(a,s) memset(a,s,sizeof(a))  
#define Write(w) freopen(w,"w",stdout)  
#define Read(r) freopen(r,"r",stdin)  
#define Pln() printf("\\n")  
#define I\_de(x,n)for(int i=0;i<n;i++)printf("%d ",x\[i\]);Pln()  
#define De(x)printf(#x"%d\\n",x)  
#define For(i,x)for(int i=0;i<x;i++)  
#define CON(x,y) x##y  
#define Pmz(dp,nx,ny)for(int hty=0;hty<ny;hty++){for(int htx=0;htx<nx;htx++){\\  
    printf("%d ",dp\[htx\]\[hty\]);}Pln();}  
#define M 10000005  
#define PII pair<int,int\>  
#define PB push\_back  
#define oo INT\_MAX  
#define Set\_oo 0x3f  
#define Is\_debug true  
#define debug(...) if(Is\_debug)printf("DEBUG: "),printf(\_\_VA\_ARGS\_\_)  
#define FOR(it,c) for(\_\_typeof((c).begin()) it=(c).begin();it!=(c).end();it++)  
#define eps 1e-6  
bool xdy(double x,double y){return x>y+eps;}  
bool xddy(double x,double y){return x>y-eps;}  
bool xcy(double x,double y){return x<y-eps;}  
bool xcdy(double x,double y){return x<y+eps;}  
int min3(int x,int y,int z){  
    int tmp=min(x,y);  
    return min(tmp,z);  
}  
int max3(int x,int y,int z){  
    int tmp=max(x,y);  
    return max(tmp,z);  
}  
int n;  
bool seize\[M\];  
vector<int\> se;  
void pre(){  
    Set(seize,0);  
    for(int i=2;i<M;i++){  
        if(!seize\[i\]){  
            se.PB(i);  
            for(int j=i+i;j<M;j+=i){  
                seize\[j\]=1;  
            }  
        }  
    }  
}  
void solve(){  
    int len=se.size();  
    Int ans=0;  
    for(int i=0;;i++){  
        int k=n-se\[i\];  
        int l=0;  
        int r=len-1;  
        while(r>=l){  
            int mid=(r+l)>>1;  
//            debug("%d",mid);  
  
            if(se\[mid\]>k){  
                r=mid-1;  
            }else if(se\[mid\]<k){  
                l=mid+1;  
            }else{  
                r=mid;  
                break;  
            }  
        }  
        if(i>=r)break;  
        ans+=r-i;  
    }printf("%lld\\n",ans);  
}  
int main() {  
    ios\_base::sync\_with\_stdio(0);  
    pre();  
    int ff=0;  
    while(~scanf("%d",&n)&&n){  
        printf("案例 %d: ",++ff);  
        solve();  
    }  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
}