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#include <cstdio>
#include <cstdint>
#include <vector>
#include <bitset>
#include <tuple>
#include <algorithm>
#include <climits>

using namespace std;

long long n,m,s;

vector<pair<long long, long long>> vec;


int main ()
{
    scanf("%lld %lld %lld", &n, &m, &s);
    vec.push_back(make_pair(-1, 0));
    for(int i = 0; i < m; ++i)
    {
        long long a,b;
        scanf("%lld %lld",&a,&b);
        vec.push_back(make_pair(a,b));
    }
    vec.push_back(make_pair(n+1, n+2));
    sort(vec.begin(), vec.end());


    long long bestDistance = LLONG_MAX;
    long long bestP = -2;
    for (int i = 1; i<=m; ++i)
    {
        if (vec[i-1].second < vec[i].first - 1)
        {
            long long lastFree = vec[i].first - 1;
            //there is a gap before
            long long currentDistance = abs(s - lastFree);
            if(currentDistance < bestDistance)
            {
                bestP = lastFree;
                bestDistance = currentDistance;
            }
        }
        if (vec[i].second < vec[i+1].first - 1)
        {
            long long lastFree = vec[i].second + 1;
            //there is a gap after
            long long currentDistance = abs(s - lastFree);
            if(currentDistance < bestDistance)
            {
                bestP = lastFree;
                bestDistance = currentDistance;
            }
        }
    }


    printf("%lld\n", bestP);
}