#include <iostream>
#include <vector>
#include <algorithm>
#include <fstream>
#include <unordered_map>
#include <set>
#include <string>
using namespace std;
const string file = "c";
ifstream fin(file + ".in");
ofstream fout(file + ".out");
struct rectangles {
int a;
int b;
int used;
};
int n;
vector<rectangles> r;
typedef long long mare;
mare Arie;
int b = -1;
vector<int> sol;
unordered_map<int,set<int>> fr;
unordered_map<int, bool> already_added;
void reading() {
cin >> n;
r.resize(n + 1);
for(int i = 1; i <= n; i++) {
cin >> r[i].a >> r[i].b;
Arie += 1LL * r[i].a * r[i].b;
b = max(b, r[i].b);
}
}
bool canBeSeparated(mare l, mare L) {
while(1LL * l * L) {
if(!fr[l].empty()) {
int ind = *(fr[l].rbegin());
fr[l].erase(ind);
if(r[ind].a != r[ind].b)
fr[(r[ind].a == l ? r[ind].b : r[ind].a)].erase(ind);
r[ind].used = 0;
if(r[ind].a == l)
L -= r[ind].b;
else
L -= r[ind].a;
} else {
if(fr[L].empty()) return 0;
int ind = *(fr[L].rbegin());
fr[L].erase(ind);
if(r[ind].a != r[ind].b)
fr[(r[ind].a == L ? r[ind].b : r[ind].a)].erase(ind);
r[ind].used = 0;
if(r[ind].a == L)
l -= r[ind].b;
else
l -= r[ind].a;
}
}
return 1;
}
void add_missing() {
for(int i = 1; i <= n; i++) {
if(r[i].used == 0) {
fr[r[i].a].insert(i);
if(r[i].b != r[i].a) fr[r[i].b].insert(i);
r[i].used = 1;
}
}
}
void tryMargin(int l) {
if( Arie % l || already_added[min(Arie / l, 1LL * l)]) return;
add_missing();
if(canBeSeparated(min(1LL * l, Arie / l), max(1LL * l, Arie / l))) {
sol.push_back(min(1LL * l, Arie / l));
already_added[min(1LL * l, Arie / l)] = 1;
}
}
int main() {
reading();
for(int i = 1; i <= n; i++) {
tryMargin(r[i].a);
tryMargin(r[i].b);
}
cout << sol.size() << '\n';
sort(sol.begin(), sol.end());
for(auto x: sol) {
cout << x << "\n";
}
}
