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#include<bits/stdc++.h>
using namespace std;
int main()
{
    ios_base::sync_with_stdio(0);
    cout.tie(0);
    cin.tie(0);
    long long n, m, s;
    cin>>n>>m>>s;
    vector<pair<long long, long long>>a(m);
    for(int i=0; i<m; i++)
    {
        long long c, b;
        cin>>c>>b;
        a[i]={c, b};
    }
    sort(a.begin(), a.end());
    pair<long long, long long> mini={n+1, -1};
    if(a[0].first>1)
        mini={abs(s-a[0].first+1), a[0].first-1};
    for(int i=1; i<m; i++)
    {
        if(a[i-1].second+1!=a[i].first)
            mini=min(mini, min((pair<long long, long long>){abs(a[i-1].second+1-s), a[i-1].second+1}, (pair<long long, long long>){abs(a[i].first-1-s), a[i].first-1}));
    }
    if(a.back().second<n)
        mini=min(mini, (pair<long long, long long>){abs(a.back().second+1-s), a.back().second+1});
    cout<<mini.second;
}