#include <bits/stdc++.h>

#define pb push_back
typedef long long LL;

using namespace std;

vector<pair<LL,LL>> v;
vector<pair<LL,LL>> v2;


int main()
{
    LL n, m, s;
    cin >> n >> m >> s;
    for(int i=1;i<=m;i++)
    {
        LL a, b;
        cin >> a >> b;
        v.pb({a,b});
    }

    sort(v.begin(), v.end());
    int it=0;
    for(int i=0;i<m;i++)
    {
        auto [a,b] = v[i];
        while(i+1 < m && v[i+1].first <= b+1)
        {
            b = max(b, v[i+1].second);
            i++;
        }

        v2.pb({a,b});
    }

    for(int i=0;i<v2.size();i++)
    {
        auto [a,b] = v2[i];
        if(a <= s && s <= b)
        {
            LL l = (a-1 >= 1 ? a-1 : -1);
            LL r = (b+1 <= n ? b+1 : -1);
            if(l == -1)
            {
                cout << r;
                return 0;
            }
            if(r == -1)
            {
                cout << l;
                return 0;
            }
            if((s - l) <= (r - s))
            {
                cout << l;
                return 0;
            }
            else
            {
                cout << r;
                return 0;
            }
        }
    }
    return 0;
}