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#include <bits/stdc++.h>

using namespace std;
using ll = long long;

ll n; // liczba budynków
int m; // liczba przedziałów
ll s; // numer budynku, w którym jest szkoła

vector<pair<ll,ll>> intervals;

ll dist(ll x) {
    return abs(x - s);
}

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

    cin >> n >> m >> s;

    for (int i=0; i<m; i++) {
        ll l, r;
        cin >> l >> r;
        intervals.push_back({ l, r });
    }

    sort(intervals.begin(), intervals.end());

    int idx_s = 0;
    for (int i=0; i<m; i++) {
        const auto& [l, r] = intervals[i];
        if (l <= s && s <= r) {
            idx_s = i;
            break;
        }
    }

    int i = idx_s - 1;
    ll ans_right = -1;
    while (i < m) {
        i++;
        const auto& [l, r] = intervals[i];
        if (i == m-1) {
            if (r+1 <= n) {
                ans_right = r + 1;
                break;
            }
        }
        else {
            const auto& [l_, r_] = intervals[i+1];
            if (r+1 < l_) {
                ans_right = r + 1;
                break;
            }
        }
    }

    i = idx_s + 1;
    ll ans_left = -1;
    while (i >= 0) {
        i--;
        const auto& [l, r] = intervals[i];
        if (i == 0) {
            if (1 < l) {
                ans_left = l - 1;
                break;
            }
        }
        else {
            const auto& [_l, _r] = intervals[i-1];
            if (_r < l-1) {
                ans_left = l - 1;
                break;
            }
        }
    }

    if (ans_left != -1 && (dist(ans_left) <= dist(ans_right) || ans_right == -1)) {
        cout << ans_left << "\n";
    }
    else {
        cout << ans_right << "\n";
    }
}