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#include <bits/stdc++.h>


using namespace std;


long long solve(long long n, int m, long long s, vector <pair<long long, long long>> &segs) {
    vector <long long> cands;
    for (auto &[l, r] : segs) {
        if (l > 1) cands.push_back(l - 1);
        if (r < n) cands.push_back(r + 1);
    }

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

    long long ans = -1, ansDist = n;
    for (auto c : cands) {
        bool covered = false;
        for (auto [l, r] : segs) if (l <= c && c <= r) {
            covered = true;
            break;
        }

        if (!covered) {
            long long dist = abs(s - c);
            if (dist < ansDist) {
                ans = c;
                ansDist = dist;
            }
        }
    }

    return ans;
}

int main() {
    ios_base::sync_with_stdio(false);

    long long n, s;
    int m;

    cin >> n >> m >> s;

    vector <pair<long long, long long>> segs(m);
    for (auto &[l, r] : segs) {
        cin >> l >> r;
    }

    cout << solve(n, m, s, segs);

    return 0;
}