#include <bits/stdc++.h> #define int long long #define pll pair<int,int> #define endl '\n' using namespace std; const int MOD2=998244353; const int MOD1=1e9+7; const int N=3e5+7; const int LOG=20; const long long inf=8e18+7; int l[N],r[N]; vector<pll>v; int dfs(int k,int a,int b, int n){ if(k >= n){ return 0; } if(k==n-1) v.push_back({a,b}); if(a==l[k-1]){ return dfs(k+1,a,b+r[k-1], n)+1; } if(a==r[k-1]){ return dfs(k+1,a,b+l[k-1], n)+1; } if(b==l[k-1]){ return dfs(k+1,a+r[k-1],b, n)+1; } if(b==r[k-1]){ return dfs(k+1,a+l[k-1],b, n)+1; } return 0; } signed main() { ios_base::sync_with_stdio(0), cin.tie(0); int n; cin>> n; for(int i=0;i<n;i++){ cin>> l[i]>>r[i]; } dfs(1,l[1],r[1],n); // if(aa==l[n-1]){ // v.push_back(min(aa,bb+r[n-1])); // } // if(aa==r[n-1]){ // v.push_back(min(aa,bb+l[n-1])); // } // if(bb==l[n-1]){ // v.push_back(min(aa+r[n-1],bb)); // } // if(bb==r[n-1]){ // v.push_back(min(aa+l[n-1],bb)); // } vector<int>ans; for(int i=0;i<v.size();i++){ int aa=v[i].first,bb=v[i].second; if(aa==l[n-1]){ ans.push_back(min(aa,bb+r[n-1])); } if(aa==r[n-1]){ ans.push_back(min(aa,bb+l[n-1])); } if(bb==l[n-1]){ ans.push_back(min(aa+r[n-1],bb)); } if(bb==r[n-1]){ ans.push_back(min(aa+l[n-1],bb)); } } cout<< ans.size()<<endl; sort(ans.begin() , ans.end()); for(int i: ans){ cout<< i<<endl; } }