#include <bits/stdc++.h> using namespace std; bool a(int n){ bool l=true; if(n<=2) l=false; else { for(int j=2;j<=sqrt(n);j++){ if(n%j==0){ l=false; break; } } } return l; } int main(){ int i,n; cin>>n; for(i=1;i<=n-2;i++){ if(a(i)&&a(i+2)){ cout<<i<<" "<<i+2<<endl; } } return 0; } /************************************************************** Problem: 1139 User: fzy001 Language: C++ Result: Accepted Time:12 ms Memory:2072 kb ****************************************************************/