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#include <algorithm>
#include <cstdint>
#include <iostream>
#include <vector>

std::vector<std::pair<int64_t, int64_t>> segments;

int main() {

    int64_t n, m, s;
    std::cin >> n >> m >> s;

    segments.reserve(m);

    for (int i = 0; i < m; i++) {
        int64_t l, r;
        std::cin >> l >> r;
        
        segments.push_back(std::make_pair(l, r));
    }

    std::sort(segments.begin(), segments.end());

    int64_t bestIndex=-1;
    int64_t bestDistance=n+1;

    for (int i = 0; i < m; i++) {
        // check left end
        int64_t prevRight = (i > 0 ? segments[i-1].second : 0);
        // if (i > 0 && segments[i-1].second == segments[i].first) { // left end not valid

        if (segments[i].first - 1 > prevRight) {
            auto dist = std::abs(segments[i].first - 1 - s);
            if (dist < bestDistance) {
                bestDistance = dist;
                bestIndex = segments[i].first - 1;
            }
        }

        int64_t nextLeft = (i < m - 1 ? segments[i + 1].first: n + 1);

        if (segments[i].second + 1 < nextLeft) {
            auto dist = std::abs(segments[i].second + 1 - s);
            if (dist < bestDistance) {
                bestDistance = dist;
                bestIndex = segments[i].second + 1;
            }
        }
    }

    std::cout << bestIndex;

    return 0;
}