#include <bits/stdc++.h> using namespace std; bool ss(int n){ bool r=true; if(n<=2) r=false; else { for(int j=2;j<=sqrt(n);j++){ if(n%j==0){ r=false; break; } } } return r; } int main(){ int i,n; cin>>n; for(i=1;i<=n-2;i++){ if(ss(i)&&ss(i+2)){ cout<<i<<" "<<i+2<<endl; } } return 0; } /************************************************************** Problem: 1139 User: chenlingxuan Language: C++ Result: Accepted Time:14 ms Memory:2072 kb ****************************************************************/