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#include <algorithm>
#include <bitset>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>

using namespace std;

#define PB push_back
#define MP make_pair
#define F first
#define S second
#define ALL(x) (x).begin(),(x).end()
#define SIZE(x) (int)(x).size()
#define CLEAR(tab) memset(tab, 0, sizeof(tab))
#define REP(x, n) for(int x = 0; x < (n); x++)
#define FOR(x, b, e) for(int x = (b); x <= (e); x++)
#define FORD(x, b, e) for(int x = (b); x >= (e); x--)
#define VAR(v, n) __typeof(n) v = (n)
#define FOREACH(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define DEBUG(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)

typedef long long int LL;
typedef pair<int,int> PII;
typedef vector<int> VI;

const int MXN = 1010;
const int C = 262144;
const LL INF = 1LL<<62;
const int MOD = 1000000007;

LL n, s;
int m;
pair<LL, LL> interval[MXN];

LL calc(LL x, LL y) {
    if(x > y)
        return x - y;
    return y - x;
}

void test() {
    scanf("%lld %d %lld", &n, &m, &s);
    FOR(i, 1, m) {
        int a, b;
        scanf("%lld %lld", &interval[i].F, &interval[i].S);
    }
    sort(interval + 1, interval + m + 1);
    vector<pair<LL, LL> > merged;
    FOR(i, 1, m) {
        pair<LL, LL> curr = interval[i];
        int iter = i + 1;
        while(iter <= m && curr.S + 1 == interval[iter].F) {
            curr.S = interval[iter].S;
            iter++;
        }
        i = iter - 1;
        merged.PB(curr);
    }
    LL dist = INF;
    LL pos = -1;
    FOREACH(it, merged) {
        LL tmp = calc(it -> F - 1, s);
        if(tmp < dist && it -> F - 1 > 0) {
            dist = tmp;
            pos = it -> F - 1;
        }
        tmp = calc(it -> S + 1, s);
        if(tmp < dist && it -> S + 1 <= n) {
            dist = tmp;
            pos = it -> S + 1;
        }
    }
    printf("%lld\n", pos);
}

int main() {
	int te = 1;
	//scanf("%d", &te);
	while(te--)
		test();
	return 0;
}