#include <bits/stdc++.h>
using namespace std;
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii ;
typedef pair<ll, ll> pll ;
typedef vector<pii> vii ;
typedef vector<int> veci ;
typedef vector<pll> vll ;
typedef vector<ll> vecll;
// find_by_order order_of_key
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define Mp make_pair
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " = " << x << endl
#define set_dec(x) cout << fixed << setprecision(x);
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("in.txt" , "r" , stdin) ; freopen("out.txt" , "w" , stdout);
#define lb lower_bound
#define ub upper_bound
#define for1(n) for(int i=1;i<=n;i++)
#define for0(n) for(int i=0;i<n;i++)
#define forn(n) for(int i=n;i>0;i--)
#define pq priority_queue <pii, vector<pii>, greater<pii>>
const ll mod = 1e9+7 ;// 998244353 ;// 1e9+9;
ll inf=1e18;
const int N=5e6+10,L=21,bs=701,NN=1e6;
int A[N],B[N],D[N],E[N],n,m,k,q,dp[N],pre[N],dist[N],vis[N];
vector<int>g[N];
multiset<int>C[N];
bool solve(ll a,ll b){
if(min(a,b)==0)return 1;
if(a>=N || C[a].size()==0)return 0;
vector<int>vec;
for(int t:C[a]){
if(t!=a)C[t].erase(C[t].find(a));
vec.pb(t);
b-=t;
}
C[a].clear();
bool o=solve(b,a);
for(int x:vec){
if(x!=a)
C[x].insert(a);
C[a].insert(x);
}
return o;
}
int main(){
fast_io
cin>>n;
vector<int>vec;
ll sum=0;int mn=0;
for1(n){
int x,y;cin>>x>>y;
C[x].insert(y);
if(x!=y)
C[y].insert(x);
sum+=1ll*x*y;
vec.pb(x);vec.pb(y);
mn=max(mn,min(x,y));
}
sort(all(vec));vec.resize(unique(all(vec))-vec.begin());
vector<int>ans;
for(int x:vec){
if(x>=mn && sum%x==0){
solve(x,sum/x);
ans.pb(min(ll(x),sum/x));
}
}
sort(all(ans));ans.resize(unique(all(ans))-ans.begin());
cout<<ans.size()<<endl;
for(int x:ans)cout<<x<<endl;
}
