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#include <cstdio>
#include <vector>
#include <algorithm>

long long int n, m, s;
std::vector<std::pair<long long int, long long int>> Q;

long long int find_building()
{
    int i;
    long long int last, left = -1, right = -1;

    /* school location */
    for (i = 0; i < m; ++i) {
        if (s >= Q[i].first && s <= Q[i].second)
            break;
    }

    /* assume we found it */

    /* left */
    last = Q[i].first;
    for (int j = i - 1; j >= 0; --j) {
        if (Q[j].second + 1 < last) {
            left = last - 1;
            break;
        }
    
        last = Q[j].first;
    }

    if (left == -1 && Q[0].first > 1)
        left = Q[0].first - 1;

    /* right */
    last = Q[i].second;
    for (int j = i + 1; j < m; ++j) {
        if (Q[j].first - 1 > last) {
            right = last + 1;
            break;
        }

        last = Q[j].second;
    }

    if (right == -1 && Q[m-1].second < n)
        right = Q[m-1].second + 1;

    if (right > 0) {
        if (right - s < s - left || left <= 0)
            return right;
    }
    
    return left;
}

int main()
{
    scanf("%lld%lld%lld", &n, &m, &s);

    Q.resize(m);
    for (int i = 0; i < m; ++i) {
        long long int a, b;
        scanf("%lld%lld", &Q[i].first, &Q[i].second);


    }

    std::sort(Q.begin(), Q.end());
    printf("%lld\n", find_building());
    return 0;
}