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#include <bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
using namespace std;

using ll = long long;
using ld = long double;

#define int ll
#define sz(x) ((int)(x).size())

using pii = pair<int,int>;
using tii = tuple<int,int,int>;

signed main() {
   cin.tie(0) -> sync_with_stdio(0);
   int n, m, s;
   cin >> n >> m >> s;
   map<int, int> segm;
   for(int i = 0, l, r; i < m; i++) {
      cin >> l >> r;
      segm[l] = r;
   }
   
   int rez = -1;
   auto trypoz = [&](int x) {
      if(x < 1 || x > n) return;
      auto it = segm.upper_bound(x);
      if(it == segm.begin());
      else {
         it = prev(it);
         if(it -> first <= x && x <= it -> second) return;
      }
      if(rez == -1) rez = x;
      else if(abs(rez - s) > abs(x - s)) rez = x;
      else if(abs(rez - s) == abs(x - s) && x < rez) rez = x;
      return;
   }; 
   
   
   for(auto [l, r] : segm) {
      trypoz(l - 1);
      trypoz(r + 1);
   }
   
   cout << rez << '\n';
   
   
}

/**
      Binecuvanteaza Doamne Ukraina.
--
*/