#include <bits/stdc++.h>

#define rep(i, a, b) for (int i = a; i <= b; ++i)
#define per(i, b, a) for (int i = b; i >= a; --i)

#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()

using namespace std;

typedef long long ll;
typedef vector< int > vi;
typedef pair< int, int > pii;
typedef long double ld;

const int oo = 0x3f3f3f3f;
const ll mod = 1000000007LL;

int n;
set < pii > st;

int main() {
    cin >> n;
    rep (i, 1, n) {
        int a, b;
        cin >> a >> b;
        if (sz(st) == 0) {
            st.insert({a, b});
            continue;
        }
        pii el = *(--st.upper_bound({a, b}));
        st.erase(st.find(el));
        int c = el.first;
        int d = el.second;
        if (c <= b && d >= a) {
            st.insert({max(a, c), min(b, d)});
        } else {
            st.insert({a, b});
            st.insert({c, d});
        }
    }

    cout << sz(st) << '\n'   ;
    for (auto x : st) cout << x.first << ' ';
    cout << '\n';

//  cerr << fixed() << setprecision(3) << (ld)clock() / (ld)CLOCKS_PER_SEC << '\n';
    return 0;
}