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#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>

//#pragma GCC optimize("O0")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,tune=native")
#pragma GCC optimize("unroll-loops")

using namespace std;
//using namespace __gnu_pbds;

#define pb push_back
#define F first
#define S second
#define ll long long
#define ld double long
#define ull unsigned long long
#define endl '\n'


const ll N = 3e5 + 36;
const ll M = 2e3 + 36;
const ll INF = 1e9 + 7;
const ll MOD = 1e9 + 7;
const ll MOD1 = 888888901;
const ll MOD2 = 999988901;
const ll X[8] = {1, -1, 2, 2, -2, -2, 1, -1};
const ll Y[8] = {2, 2, 1, -1, 1, -1, -2, -2};
const ld PI = 3.14159265358979323846;
const ld EPS = 1e-10;

//tree < pair < string, int >, null_type, less < pair < string, int > >, rb_tree_tag, tree_order_statistics_node_update > a;

//mt19937 gen(chrono::system_clock::now().time_since_epoch().count());
mt19937 gen(19937);


signed main() {
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#else
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);
#endif // LOCAL
    ll n, m, s;
    cin >> n >> m >> s;
    vector<pair<ll,ll>> a((int)m);
    for (int i(0); i < m; ++i) {
      cin >> a[i].F >> a[i].S;
    }
    sort(a.begin(), a.end());
    pair<ll, ll> ans = {(ll)1e13, -1};
    set<ll> st;
    bool sl = true, sr = true;
    for (int i(0); i < m; ++i){
       st.erase(a[i].F);
       st.insert(a[i].F - 1);
       st.insert(a[i].S + 1);
       if (i) {
          st.erase(a[i - 1].S);
       }
       if (a[i].F <= s - 1 && a[i].S >= s - 1) {
          sl = 0;
       }
       if (a[i].F <= s + 1 && a[i].S >= s + 1) {
          sr = 0;
       }
    }
    
    st.erase(0);
    st.erase(n + 1);
    //cout << sl << ' ' << sr << endl;
    if (sl && s - 1 > 0) {
       ans = min(ans, {1, s - 1});
    }
    if (sr && s + 1 <= n) {
       ans = min(ans, {1, s + 1});
    }
    for (auto to : st) {
       //cout << to << endl;
       if (s != to)
       ans = min(ans, {abs(s - to), to});
    }
    
    cout << ans.S << endl;
    return 0;
}