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#include <bits/stdc++.h>

using namespace std;

int main()
{
    long long n,s;
    int m;
    cin >> n >> m >> s;
    vector<pair<long long, long long>> taken(m);
    for(int i = 0; i < m; i++)
    {
        cin >> taken[i].first >> taken[i].second;
    }
    sort(taken.begin(), taken.end());

    long long minimum = 1e13;
    long long min_pos = -1;
    for(int i = 0; i < m; i++)
    {
        if(taken[i].first <= s && s <= taken[i].second)
        {
            int right = i;
            int left = i;
            while(right < m - 1)
            {
                if(taken[right].second + 1 < taken[right + 1].first)
                {
                    break;
                }
                right++;
            }
            while(left > 0)
            {
                if(taken[left].first - 1 > taken[left - 1].second)
                {
                    break;
                }
                left--;
            }
            if(taken[left].first != 1)
            {
                minimum = s - (taken[left].first - 1);
                min_pos = taken[left].first - 1;
            }
            if(taken[right].second != n)
            {
                if((taken[right].second + 1) - s < minimum)
                {
                    minimum = (taken[right].second + 1);
                    min_pos = taken[right].second + 1;
                }
            }
            break;
        }
    }
    cout << min_pos;
}