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#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;
using u128 = unsigned __int128;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    i64 n, s;
    int m;
    std::cin >> n >> m >> s;
    
    std::vector<std::array<i64, 2>> a(m);
    for (int i = 0; i < m; i++) {
        i64 l, r;
        std::cin >> l >> r;
        a[i] = {l, r};
    }
    std::sort(a.begin(), a.end());
    
    std::array<i64, 2> ans {n, n};
    for (int i = 0; i < m; i++) {
        auto [l, r] = a[i];
        if (l - 1 > (i ? a[i - 1][1] : 0)) {
            ans = std::min(ans, std::array {std::abs(l - 1 - s), l - 1});
        }
        if (r + 1 < (i < m - 1 ? a[i + 1][0] : n + 1)) {
            ans = std::min(ans, std::array {std::abs(r + 1 - s), r + 1});
        }
    }
    std::cout << ans[1] << "\n";
    
    return 0;
}