#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
using LL = long long;

int main(){

#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

    int n, m, x;
    cin >> n >> m >> x;
    vector<pair<int, int> > p(m);
    for(auto &[l, r] : p) cin >> l >> r;
    vector<int> ans;
    // 向左
    {
        vector<bool> ed(n + 1);
        vector<int> d(n + 1);
        for(auto [l, r] : p){
            r = min(r, x);
            if (l >= r) continue;
            ed[l] = true;
            d[l + 1] += 1;
            d[r + 1] -= 1;
        }
        for(int i = 1; i <= x; i++){
            d[i] += d[i - 1];
        }
        for(int i = x - 1; i >= 1; i--){
            if (d[i + 1] == 0) break;
            if (ed[i]) ans.push_back(i);
        }
    }
    // 向右
    {
        vector<bool> ed(n + 1);
        vector<int> d(n + 1);
        for(auto [l, r] : p){
            l = max(l, x);
            if (l >= r) continue;
            ed[r] = true;
            d[l] += 1;
            d[r] -= 1;
        }
        for(int i = x; i <= n; i++){
            d[i] += d[i - 1];
        }
        for(int i = x + 1; i <= n; i++){
            if (d[i - 1] == 0) break;
            if (ed[i]) ans.push_back(i);
        }
    }
    sort(ans.begin(), ans.end());
    for(int i = 0; i < ans.size(); i++){
        cout << ans[i] << " \n"[i + 1 == ans.size()];
    }

}