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#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vi> vvi;
typedef vector<bool> vb;

#define eb emplace_back
#define pb push_back
#define loop(i, a, b) for (int i = a; i < b; i++)
#define rloop(i, a, b) for (int i = a; i >= b; i--)
#define all(x) (x).begin(), (x).end()

int main()
{
    cin.tie(0)->sync_with_stdio(false);

    ll n, m, s, a, b, wyn = -3ll;

    vector<pair<ll, ll>> wek;

    cin >> n >> m >> s;

    loop(i, 0, m)
    {
        cin >> a >> b;
        wek.pb({ a,b });
    }

    wek.pb({ s,s });
    for (pair<ll, ll>& par : wek)
    {
        ll potL = par.first - 1ll, potR = par.second + 1ll;

        if (potR <= n)
        {
            bool ok = true;
            for (pair<ll, ll>& par2 : wek)
            {
                if (par2.first <= potR && par2.second >= potR)
                {
                    ok = false;
                    break;
                }
            }
            if (ok)
                if (abs(s - wyn) > abs(s - potR) || (abs(s - wyn) == abs(s - potR) && potR < wyn) || wyn==-3ll)
                    wyn = potR;
        }
        if (potL > 0)
        {
            bool ok = true;
            for (pair<ll, ll>& par2 : wek)
            {
                if (par2.first <= potL && par2.second >= potL)
                {
                    ok = false;
                    break;
                }
            }
            if (ok)
                if (abs(s - wyn) > abs(s - potL) || (abs(s-wyn)==abs(s-potL) && potL<wyn) || wyn == -3ll)
                    wyn = potL;
        }
    }

    cout << wyn << endl;
    return 0;
}