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// clang-format off
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ssize(x) int(x.size())
template<class A,class B>auto&operator<<(ostream&o,pair<A,B>p){return o<<'('<<p.first<<", "<<p.second<<')';}
template<typename T,typename = typename enable_if<!is_same<T,string>::value>::type>
auto operator<<(ostream&o,T x)->decltype(x.end(),o){o<<'{';int i=0;for(auto e:x)o<<(", ")+2*!i++<<e;return o<<'}';}
#ifdef DEBUG
#define debug(x...) cerr<<"["#x"]: ",[](auto...$){((cerr<<$<<"; "),...);}(x),cerr<<'\n'
#else
#define debug(...) {}
#endif
// clang-format on

vector<pair<ll, ll>> intervals;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    ll n, m, s, a, b;
    cin >> n >> m >> s;
    intervals.push_back({0, 0});
    for (int i = 1; i <= m; i++)
    {
        cin >> a >> b;
        intervals.push_back({a, b});
    }
    sort(intervals.begin(), intervals.end());
    intervals.push_back({n + 1, n + 1});
    ll min_dist = n, ans = -1;
    for (int i = 1; i <= m; i++)
    {
        if (intervals[i - 1].second < intervals[i].first - 1)
        {
            if (abs(s - (intervals[i].first - 1)) < min_dist)
            {
                min_dist = abs(s - (intervals[i].first - 1));
                ans = intervals[i].first - 1;
            }
        }
        if (intervals[i].second + 1 < intervals[i + 1].first)
        {
            if (abs(s - (intervals[i].second + 1)) < min_dist)
            {
                min_dist = abs(s - (intervals[i].second + 1));
                ans = intervals[i].second + 1;
            }
        }
    }

    cout << ans << '\n';

    return 0;
}