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#include <iostream>
#include <utility>
#include <set>

struct InputData {
    uint64_t n;
    uint64_t m;
    uint64_t school;
    std::set<std::pair<uint64_t, uint64_t>> ranges;
} input_data;

void parse_input() {
    std::cin >> input_data.n >> input_data.m >> input_data.school;
    for (uint64_t i = 0; i < input_data.m; ++i) {
        uint64_t l, r;
        std::cin >> l >> r;
        input_data.ranges.emplace(l, r);
    }
}

uint64_t solve() {
    uint64_t res;
    uint64_t res_dist = input_data.n<<1;
    auto range_it = input_data.ranges.cbegin();
    for (uint64_t i = 1; i <= input_data.n; ++i) {
        if (range_it != input_data.ranges.cend() && i == range_it->first) {
            i = range_it->second;
            input_data.ranges.erase(range_it);
            range_it = input_data.ranges.cbegin();
            continue;
        }

        const uint64_t d = i > input_data.school ? i - input_data.school : input_data.school - i;
        // std::cerr << i << ' ' << d << ' ' << res << ' ' << res_dist << ' ';
        if (d < res_dist) {
            // std::cerr << "yes";
            res = i;
            res_dist = d;
        }
        // std::cerr << '\n';
        
    }
    return res;
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(NULL);
    parse_input();
    std::cout << solve(); //<< '\n';

    return 0;
}

// 708007 708988
// 709253 709765
// 709579