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#include <algorithm>
#include <iostream>
#include <vector>

using namespace std;
using LL = long long;
using PLL = pair<LL, LL>;

LL solve(LL n, LL s, vector<PLL>& intervals)
{
    sort(intervals.begin(), intervals.end());

    vector<PLL> united_intervals;
    united_intervals.push_back(intervals[0]);

    for (size_t i = 1; i < intervals.size(); ++i)
    {
        if (intervals[i].first == united_intervals.back().second + 1)
            united_intervals.back().second = intervals[i].second;
        else
            united_intervals.push_back(intervals[i]);
    }

    for (size_t i = 0; i < united_intervals.size(); ++i)
    {
        if (s >= united_intervals[i].first && s <= united_intervals[i].second)
        {
            LL res = united_intervals[i].first - 1;

            if (res == 0 || (united_intervals[i].second < n && united_intervals[i].second + 1 - s < s - res))
                res = united_intervals[i].second + 1;

            return res;
        }
    }

    return -1;
}

int main()
{
    LL n, s, l, r;
    int m;
    cin >> n >> m >> s;

    vector<PLL> intervals;

    for (int i = 0; i < m; ++i)
    {
        cin >> l >> r;

        intervals.push_back(make_pair(l, r));
    }

    LL res = solve(n, s, intervals);

    cout << res << endl;

    return 0;
}