#include<bits/stdc++.h> using namespace std; int sushu(int n) { int cnt = 0; for(int i=2;i<=sqrt(n);i++) { if(n%i==0) { cnt++; break; } } if(cnt==0&&n>1)return 1; else return 0; } int main() { int n; cin>>n; for(int i=1;i<=n-2;i++) { for(int j=1;j<=n;j++) { if(sushu(j)==1&&sushu(i)==1&&j-i==2) { cout<<i<<" "<<j<<endl; } } } } /************************************************************** Problem: 1139 User: wangyuxin Language: C++ Result: Accepted Time:16 ms Memory:2072 kb ****************************************************************/