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#include "bits/stdc++.h"
using namespace std;

using ll = long long;
#define all(x) x.begin(), x.end()

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    ll n, m, s;
    cin >> n >> m >> s;
    vector <pair <ll, ll>> v(m);
    for (auto &[a, b] : v) {
        cin >> a >> b;
    }
    sort(all(v));

    ll ans = -1e18;
    for (int i = 0; i < m; i++) {
        if (i == 0 || v[i].first - 1 > v[i - 1].second) {
            if (abs(ans - s) > abs(v[i].first - 1 - s) || (abs(ans - s) == abs(v[i].first - 1 - s) && v[i].first - 1 < ans)) {
                if (v[i].first - 1 != 0) ans = v[i].first - 1;
            }
        }
        if (i == m - 1 || v[i].second + 1 < v[i + 1].first) {
            if (abs(ans - s) > abs(v[i].second + 1 - s) || (abs(ans - s) == abs(v[i].second + 1 - s) && v[i].second + 1 < ans)) {
                if (v[i].second + 1 != n + 1) ans = v[i].second + 1;
            }
        }
    }
    cout << ans << '\n';
}