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#include <bits/stdc++.h>

#define ll long long
#define ve vector
#define fi first
#define se second
#define ld long double
#define all(x) x.begin(), x.end()

using namespace std;

typedef pair<int, int> pii;

void solve()
{
    ll n, m, s;
    cin >> n >> m >> s;
    ve<pair<ll, ll> >v(m);
    for(auto& i : v)
        cin >> i.fi >> i.se;;
    sort(all(v));
    ll res = -1;
    auto upd = [&](ll x){
        if(res == -1 || abs(res - s) > abs(x - s) || (abs(res - s) == abs(x - s) && x < res))
            res = x;
    };
    auto upd2 = [&](ll l, ll r){
        if(r < l)
            return;
        if(s >= l && s <= r)
            res = s;
        upd(l);
        upd(r);
    };
    upd2(1, v[0].fi - 1);
    for(int i = 1; i < m; i++){
        upd2(v[i - 1].se + 1, v[i].fi-1);
    }
    upd2(v.back().se+1, n);
    cout << res << "\n";
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int T = 1;
//    cin >> T;
    while (T--)
        solve();
}