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//
// Mateusz Pietrowcow
//
 
#include <bits/stdc++.h>
#include <bits/extc++.h>

using namespace std;

using ll = long long;
using uint = unsigned int;
using ull = unsigned long long;
using ii = pair<int,int>;
using uii = pair<uint,uint>;
using pll = pair<ll,ll>;
using pull = pair<ull,ull>;
using ld = long double;
using pld = pair<ld,ld>;
#define int128 __int128_t
#define uint128 __uint128_t

#define pbds __gnu_pbds
#define cxx __gnu_cxx

#define MOD 1000000007
#define MODLL 1000000007LL
#define MODULL 1000000007ULL

// best primes in the galaxy
#define MOD1 1000000007LL
#define MOD2 1000000403LL
#define MOD3 1000000787LL
#define MOD4 1000001447LL

#define INF 1'000'000'000
#define INFLL 1'000'000'000'000'000'000LL
#define INFULL 1'000'000'000'000'000'000ULL
#define timeNow() (chrono::high_resolution_clock::now().time_since_epoch().count())
#define all(x) x.begin(),x.end()
#define len(x) (int)(x.size())
#define lenl(x) (ll)(x.size())
#define inRange(x,a,b) (a <= x && x <= b)
#define fir first
#define sec second
#define self(x,y,z) y = x(y,z)


template <typename X, typename Y, typename Z>
using gp_hashmap = pbds::gp_hash_table<X,Y,Z,equal_to<X>,pbds::direct_mask_range_hashing<>,pbds::linear_probe_fn<>,pbds::hash_standard_resize_policy<pbds::hash_exponential_size_policy<>,pbds::hash_load_check_resize_trigger<>,true>>;
template <typename X, typename Y, typename Z>
using gp_hashmap_safe = pbds::cc_hash_table<X,Y,Z,equal_to<X>,pbds::direct_mod_range_hashing<>,pbds::hash_standard_resize_policy<pbds::hash_prime_size_policy,pbds::hash_load_check_resize_trigger<>,true>>;

template <typename X, typename Y, typename Z>
using cc_hashmap = pbds::cc_hash_table<X,Y,Z,equal_to<X>,pbds::direct_mask_range_hashing<>,pbds::hash_standard_resize_policy<pbds::hash_exponential_size_policy<>,pbds::hash_load_check_resize_trigger<>,true>>;
template <typename X, typename Y, typename Z>
using cc_hashmap_safe = pbds::cc_hash_table<X,Y,Z,equal_to<X>,pbds::direct_mod_range_hashing<>,pbds::hash_standard_resize_policy<pbds::hash_prime_size_policy,pbds::hash_load_check_resize_trigger<>,true>>;

template <typename X, typename Y, typename Z>
using indexed_set = pbds::tree<X, Y, Z, pbds::rb_tree_tag, pbds::tree_order_statistics_node_update>;


struct chash
{
    size_t operator()(const int& a) const
    {
        const static int rng = (int)timeNow() ^ (int)(ull)(make_unique<char>().get());
        return a ^ rng;
    }
};

namespace sol
{
    list<pll> t;
    ll n, s;
    int m;

    void read()
    {
        cin >> n >> m >> s;

        for (int i = 0; i < m; i++)
        {
            pll x;
            cin >> x.fir >> x.sec;
            t.push_back(x);
        }
    }

    pair<int,pll> join(pll a, pll b)
    {
        if (b.fir - a.sec > 1)
            return {2, a};
        return {1, {a.fir, b.sec}};
    }

    template <typename T>
    void sortuj_liste(list<T>& x)
    {
        vector<T> v = {};

        for (auto i : x) v.push_back(i);
        sort(all(v));

        x.clear();
        for (auto i : v) x.push_back(i);
    }

    void solve()
    {
        sortuj_liste(t);

        auto it = t.begin();

        while (next(it) != t.end())
        {
            if (join(*it, *next(it)).fir == 2)
            {
                it++;
                continue;
            }

            *it = join(*it, *next(it)).sec;
            t.erase(next(it));
        }

        ll best = INFLL;

        #define dist(x) abs((x)-s)

        for (auto i : t)
        {
            if (dist(best) > dist(i.fir - 1) && i.fir - 1 >= 1)
                best = i.fir - 1;
            if (dist(best) > dist(i.sec + 1) && i.sec + 1 <= n)
                best = i.sec + 1;
        }

        cout << best << '\n';
    }
};
 
int main()
{
    ios_base::sync_with_stdio(0);
    cout.tie(0);
    cin.tie(0);
 
    sol::read();
    sol::solve();
}