#include<bits/stdc++.h> using namespace std; bool ss(int n){ bool r=true; if(n<2) r=false; for(int i=2;i<=sqrt(n);i++){ if(n%i==0){ r=false; break; } } return r; } int main(){ int n; cin>>n; for(int i=2;i<=n-2;i++){ if(ss(i)&&ss(i+2)) cout<<i<<" "<<i+2<<endl; } return 0; } /************************************************************** Problem: 1139 User: lidongcheng Language: C++ Result: Accepted Time:13 ms Memory:2072 kb ****************************************************************/