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#include <bits/stdc++.h>
#define fi first
#define sc second
#define pb push_back
#define rep(i,p,k) for(int i=(p);i<(k);++i)
#define forn(i,p,k) for(int i=(p);i<=(k);++i)
#define forr(i,k,p) for(int i=(k)-1;i>=(p);--i)
#define each(a,b) for(auto&a:b)
#define all(v)  begin(v), end(v)
#define RET(smth)   return void(cout<<(smth)<<'\n');
#define sz(v) (int)v.size()
using namespace std;
using pii = pair<int,int>;
using ll = long long;
using lll = __int128_t;
using Vi = vector<int>;
#ifdef DEBUG
#include "debug.h"
#else
#define debug(...) ;
#endif

int main() {
#ifndef DEBUG
    cin.tie(0) -> sync_with_stdio(0);
#endif
    ll n,s; int m; cin >> n >> m >> s;
    ll lst = 0;
    ll bst = -1e18;
    auto check = [&](ll x) {
        if(abs(s-bst) > abs(s-x)) bst = x;
    };
    vector<pair<ll,ll>> p(m);
    for(auto &[l,r] : p) cin >> l >> r;
    sort(all(p));
    for(auto [l,r] : p) {
        if(l-1!=lst) {
            check(lst+1);
            check(l-1);
        }
        lst = r;
    }
    if(lst != n) check(lst+1);
    cout << bst << '\n';
    return 0;
}