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#include <bits/stdc++.h>

using namespace std;

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    long long n,m,s;
    cin>>n>>m>>s;
    vector<pair<long long,long long>> V(m);
    for(auto & [a,b] : V)
        cin>>a>>b;
    sort(V.begin(),V.end());
    long long s1 = s-1;
    if(s1<1)
        s1=-1;
    long long s2 = s+1;
    if(s2>n)
        s2=-1;
    for(auto [l,r] : V)
    {
        if(l<=s1 && s1 <=r)
            s1 = -1;
        if(l<=s2 && s2 <=r)
            s2 = -1;
    }
    if(s1!=-1)
    {
        cout<<s1<<'\n';
        return 0;
    }
    if(s2!=-1)
    {
        cout<<s2<<'\n';
        return 0;
    }
    long long p= -1;
    long long o = n+1000;
    for(long long i = 0 ;i < m ;i ++)
    {
        long long pot = V[i].first-1;
        if(pot<1)
            continue;
        if(i > 0)
        {
            if(V[i-1].second >= pot)
                continue;
        }
        if(abs(s - pot)<o)
        {
            o = abs(s-pot);
            p=pot;
        }
    }
    for(long long i = 0; i < m; i ++)
    {
        long long pot = V[i].second+1;
        if(pot>n)
            continue;
        if(i<m-1)
        {
            if(V[i+1].first <= pot)
                continue;
        }
        
        if(abs(s - pot)<o)
        {
            o = abs(s-pot);
            p=pot;
        }
    }
    cout<<p;
}