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#include <bits/stdc++.h>

using namespace std;
using LL = long long;
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define ssize(x) int(x.size())

template<class A, class B> auto &operator<<(ostream &o, pair<A, B> p) {
    return o << '(' << p.first << ", " << p.second << ')';
}

template<class T> auto operator<<(ostream &o, T x) -> decltype(x.end(), o) {
    o << '{'; int i = 0; for (auto e : x) o << (", ")+2*!i++ << e;
    return o << '}';
}

#ifdef DEBUG
#define debug(x...) cerr << "[" #x "]: ", [](auto... $) {((cerr << $ << "; "), ...); }(x), cerr << '\n';
#else
#define debug(...) {}
#endif


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

    LL n, s, x, y;
    int m;
    cin >> n >> m >> s;
    vector<pair<LL, LL>> seg(m);

    REP(i, m) {
        cin >> x >> y;
        seg[i] = {x, y};
    }
    seg.emplace_back(0, 0);
    seg.emplace_back(n + 1, n + 1);
    sort(seg.begin(), seg.end());

    LL ans = (LL) (1e13), place;
    FOR(i, 1, m) {
        auto [a, b] = seg[i];
        auto [_, prev] = seg[i - 1];
        auto [next, __] = seg[i + 1];

        if (prev != a - 1) {
            LL curr = abs(s - a + 1);
            if (curr < ans) {
                ans = curr;
                place = a - 1;
            }
        }
        if (next != b + 1) {
            LL curr = abs(s - b - 1);
            if (curr < ans) {
                ans = curr;
                place = b + 1;
            }
        }
    }

    cout << place << '\n';

    return 0;
}