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

using vi = vector<int>;
using vvi = vector<vi>;
using pi = pair<int, int>;
using ll = long long;
using pl = pair<ll, ll>;
#define all(x) x.begin(), x.end()

int main()
{
    ll n, s;
    int m;
    cin >> n >> m >> s;
    vector<pl> segments(m);
    for (int i = 0; i < m; i++)
    {
        cin >> segments[i].first >> segments[i].second;
    }
    segments.push_back({0, 0});
    segments.push_back({n + 1, n + 1});
    sort(all(segments));
    ll p = -1;
    ll dist = n + 1;
    for (int i = 0; i < m + 1; i++)
    {
        ll l = segments[i].second + 1;
        ll r = segments[i + 1].first - 1;
        if (l > r)
            continue;
        if (abs(l - s) < dist)
        {
            dist = abs(l - s);
            p = l;
        }
        if (abs(r - s) < dist)
        {
            dist = abs(r - s);
            p = r;
        }
    }
    cout << p << '\n';
    return 0;
}