#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
#include <set>
using namespace std;
#define int long long
signed main(signed argc, char *argv[])
{
int K, w, h, A = 0;
cin >> K;
vector<pair<int, int>> dims;
map<int, int> ws;
map<int, vector<int>> hs;
set<int> sides;
vector<int> ans;
for (int i = 0; i < K; i++)
{
cin >> w >> h;
dims.push_back({w, h});
ws[w] = i + 1;
hs[h].push_back(i);
sides.insert(w);
sides.insert(h);
A += w * h;
}
vector<bool> used(K, false);
map<int, int> hu;
for (int i : sides)
{
used = vector<bool>(K, false);
if (A % i != 0)
continue;
int j = A / i;
if (i < j)
swap(i, j);
if (binary_search(ans.begin(), ans.end(), j))
continue;
int crntw = i, crnth = j;
int numrect = 0;
auto chu = hu;
while (numrect < K)
{
if (crntw < crnth)
swap(crntw, crnth);
if (ws[crntw] != 0 && !used[ws[crntw] - 1])
{
crnth -= dims[ws[crntw] - 1].second;
numrect++;
used[ws[crntw] - 1] = true;
continue;
}
if (chu[crnth] == 0)
{
for (int i : hs[crnth])
{
if (!used[i])
{
crntw -= dims[i].first;
numrect++;
used[i] = true;
}
}
chu[crnth] = 1;
continue;
}
if (ws[crnth] != 0 && !used[ws[crnth] - 1])
{
crntw -= dims[ws[crnth] - 1].second;
numrect++;
used[ws[crnth] - 1] = true;
continue;
}
break;
}
if (numrect == K)
ans.push_back(j);
}
cout << ans.size() << '\n';
for (int i : ans)
cout << i << '\n';
}
