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#include <bits/stdc++.h>

using namespace std;

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

    long long n, m, s;
    cin >> n >> m >> s;

    vector<pair<long long, long long>> segments(m);
    for (int i = 0; i < m; ++i)
    {
        cin >> segments[i].first >> segments[i].second;
    }
    sort(segments.begin(), segments.end());

    long long best = 1e18;
    long long bestPlace = -1;

    if (segments[0].first != 1 && abs(segments[0].first - 1 - s) < best)
    {
        best = abs(segments[0].first - 1 - s);
        bestPlace = segments[0].first - 1;
    }

    for (int i = 0; i < m; ++i)
    {
        if (i > 0 && segments[i - 1].second != segments[i].first - 1)
        {
            if (abs(segments[i].first - 1 - s) < best)
            {
                best = abs(segments[i].first - 1 - s);
                bestPlace = segments[i].first - 1;
            }
        }
        if (i < m - 1 && segments[i + 1].first != segments[i].second + 1)
        {
            if (abs(segments[i].second + 1 - s) < best)
            {
                best = abs(segments[i].second + 1 - s);
                bestPlace = segments[i].second + 1;
            }
        }
    }

    if (segments[m - 1].second != n && abs(segments[m - 1].second + 1 - s) < best)
    {
        best = abs(segments[m - 1].second + 1 - s);
        bestPlace = segments[m - 1].second + 1;
    }

    cout << bestPlace << '\n';
}