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

#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
using namespace __gnu_pbds;
using namespace std;
#define pb push_back
#define st first
#define nd second
typedef long long ll;
typedef long double ld;
const ll I = 1000'000'000'000'000'000LL;
const int II = 2'000'000'000;
const ll M = 1000'000'007LL;
const int N = 1'007;
pair<ll, ll> tab[N];

ll A(ll x, ll y)
{
    if(x > y) return x - y;
    return y - x;
}

void Solve()
{
    int n; ll d, s;
    cin >> d >> n >> s;
    pair<ll, ll> ans = make_pair(I, I);
    for(int i = 1; i <= n; ++i)
        cin >> tab[i].st >> tab[i].nd;
    sort(tab + 1, tab + 1 + n);
    tab[0] = make_pair(0, 0);
    tab[n + 1] = make_pair(d + 1, d + 1);
    for(int i = 1; i <= n; ++i)
    {
        if(tab[i].st != tab[i - 1].nd + 1LL)
            ans = min(ans, make_pair(A(tab[i].st - 1LL, s), tab[i].st - 1LL));
        if(tab[i].nd != tab[i + 1].st - 1LL)
            ans = min(ans, make_pair(A(tab[i].nd + 1LL, s), tab[i].nd + 1LL));
    }
    cout << ans.nd << "\n";
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    //int t; cin >> t;
    //while(t--)
        Solve();

    return 0;
}