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#include <stdio.h>
#include <vector>
#include <utility>
#include <algorithm>
using namespace std;

int main() {
    long long n, s;
    int m;
	scanf("%lld %d %lld" ,&n, &m, &s);
    vector<pair<long long, long long>> z(m), zz;
    for (int i = 0; i < m; i++) {
        scanf("%lld %lld", &z[i].first, &z[i].second);
    }
    sort(z.begin(), z.end());
    for (int i = 0; i < m; i++) {
        if (!zz.empty() && zz.back().second + 1 == z[i].first) {
            zz.back().second = z[i].second;
        } else {
            zz.push_back(z[i]);
        }
    }
    z = zz;
    m = z.size();
    for (int i = 0; i < m; i++) if (z[i].first <= s && s <= z[i].second) {
        long long a = z[i].first - 1, b = z[i].second + 1;
        if (a == 0 || (b <= n && s - a > b - s)) a = b;
        printf("%lld\n", a);
        return 0;
    }
    printf("-1");
	return 0;
}