UVa - 10394 - Twin Primes

#include<bits/stdc++.h> using namespace std; bool status[1100000002]; void siv() { int N=20000000; int sq=sqrt(N); for(int i=4; i<=N; i+=2) status[i]=1; for(int i=3; i<=sq; i+=2) { if(status[i]==0) { for(int j=i*i; j<=N; j+=i) status[j]=1; } } status[1]=1; } vector < pair<long long int , long long int> >v; void Pair() { v.push_back(pair<long long int , long long int> (0, 0)); for(long long int i=3;i<=20000000;i+=2) { if(status[i]==0&&status[i+2]==0) { v.push_back(pair<long long int , long long int> (i, i+2)); } } } int main() { siv(); Pair(); long long int i,j,k,n,w,a,b,f; while(cin>>n) { f=0; cout<<"("<<v[n].first<<", "<<v[n].second<<")"<<endl; } return 0; }