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UVa 10742.cpp
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UVa 10742.cpp
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/*BISMILLAHIR RAHMANIR RAHIM*/
#include<bits/stdc++.h>
#define lli long long int
#define yes cout << "YES\n"
#define no cout << "NO\n"
#define ALL(x) x.begin(), x.end()
#define print(x) cout<<x<<endl;
#define PI acos(-1.0)
#define nl cout<<"\n"
#define mem(ar, val) memset(ar, val, sizeof(ar))
#define point(x) fixed<<setprecision(x)
#define printcase(n) cout << "Case " << tc << ": " << n <<endl;
#define printcaseii(n, m) cout << "Case " << tc << ": " << n << " " << m <<endl;
#define aInput(ar, n) for(int i=0; i<n; i++)cin>>ar[i];
#define vInput(v, n) for(int i=0; i<n; i++){lli xwq;cin>>xwq;v.push_back(xwq);}
#define input2D(ar, row, col) for(int i=0; i<row; i++){for(int j=0; j<col; j++){cin >> ar[i][j];}}
#define print2D(ar, row, col) for(int i=0; i<row; i++){for(int j=0; j<col; j++){cout << ar[i][j] << " ";}cout<<endl;}
#define vprint(vec) for(int i=0; i<vec.size(); i++){cout << vec[i]; (i==vec.size()-1? cout<<endl : cout<<" ");}
#define aprint(ar, n) for(int i=0; i<n; i++){cout << ar[i] << " ";}cout<<endl
#define ANUPAM_AKIB ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define execution_time cerr<<endl;int z=30;while(z--){cerr<<'-';}cerr<<endl;cerr<<point(16)<<"**Time -> "<<(double)(clock()-tStart)/CLOCKS_PER_SEC<<"fs"<<endl;
#define INPUT freopen("input.txt", "r", stdin)
#define OUTPUT freopen("output.txt", "w", stdout)
#define umap unordered_map
#define IN input()
#define yo(x) cout<<(#x)<<" = "<<(x)<<endl;
#define ff first
#define ss second
#define VEC vector<lli>
#define sz size()
using namespace std;
const lli inf = INT_MAX;
const int mod = 1000000007;
lli findLCM(lli a, lli b){return ((a*b)/__gcd(a,b));}
lli input(){lli x; cin >> x; return x;}
int digitCNT(int n){return ceil(log10(n)+0.00000001);}
string to_binary(lli num){if(num==0) return ""; return to_binary(num/2)+to_string(num%2);}
bool isPalindrome(string s){for(int i=0, j=s.size()-1; i<s.size()/2; i++, j--){if(s[i]!=s[j]) return 0;}return 1;}
bool isPrime(int n){if(n<2){return false;}if(n==2||n==3){return true;}if(n%2==0){return false;}for(lli i=3; i*i<=n; i+=2){if(n%i==0){return false;}}return true;}
bool cmp(pair<lli, int> a, pair<lli, int> b){ return a.first>b.first;}
int NUM = 1000005;
bool mark[1000005];
vector<int> prime;
void sieve(){
//true = not prime
//false = prime
for(int i=4; i<=NUM; i+=2){
mark[i]=true;
}
for(int i=3; i*i<=NUM; i+=2){
if(mark[i]==false){
for(int j=i*i; j<=NUM; j+=(i+i)){
mark[j]=true;
}
}
}
for(int i=2; i<=NUM; i++){
if(mark[i]==false){
prime.push_back(i);
}
}
}
void solve(int tc){
lli n = IN, ans=0;
if(!n) return;
for(int i=0; i<prime.sz; i++){
int x = prime[i];
int need = n - x;
if(x > n or need <= x) break;
int ind = upper_bound(ALL(prime), need) - prime.begin() - 1;
if(i!=ind){
ans += (ind - i);
}
}
printcase(ans)
solve(tc+1);
}
int main(){
ANUPAM_AKIB;
#ifndef ONLINE_JUDGE
clock_t tStart = clock();
INPUT;
OUTPUT;
#endif
sieve();
int tc = 1;
//cin >> tc; //TEST CASE
for(int i=1; i<=tc; i++){
solve(i);
}
#ifndef ONLINE_JUDGE
execution_time;
#endif
return EXIT_SUCCESS;
}