#include<bits/stdc++.h> using namespace std; int f(int n){ int sum=0; for(int i=2;i<n;i++){ if(n%i==0){ sum=sum+i+n/i; } } return sum/2; } int main(){ int n; cin>>n; for(int i=1;i<=n;i++){ if(f(i)!=0&&f(f(i))==i&&f(i)<=n){ cout<<i<<" "<<f(i)<<endl; } } return 0; } /************************************************************** Problem: 1140 User: chenmingyu Language: C++ Result: Accepted Time:10 ms Memory:2072 kb ****************************************************************/