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#include <iostream>
#include <vector>
#include <utility>
#include <algorithm>

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(NULL);
    int n, m, s;
    std::cin >> n >> m >> s;
    std::vector<std::pair<int, int>> ranges;
    ranges.assign(m + 2, {});
    for (int i = 1; i <= m; i++) {
        std::cin >> ranges[i].first >> ranges[i].second;
    }
    ranges[0] = {0, 0};
    ranges[m + 1] = {n + 1, n + 1};
    std::sort(ranges.begin(), ranges.end(), [](std::pair<int, int> a, std::pair<int, int> b) {
        return a.first < b.first;
    });
    int min = -1;
    int school_range = -1;
    for (int i = 1; i <= m; i++) {
        if(ranges[i].first <= s && ranges[i].second >= s){
            school_range = i;
            break;
        }
    }
    int i = school_range;
    while(i > 1 && ranges[i - 1].second== ranges[i].first - 1){
        i--;
    }
    if(ranges[i].first - 1 > 0 && ranges[i].first - 1 <= n){
        min = ranges[i].first - 1;
    }
    i = school_range;
    while(i < m && ranges[i + 1].first == ranges[i].second + 1){
        i++;
    }
    if(ranges[i].second + 1 > 0 && ranges[i].second + 1 <= n && (min == -1 || abs(min - s) > abs(ranges[i].second + 1 - s))){
        min = ranges[i].second + 1;
    }
    std::cout << min;
}