1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,b) for (int i = (a); i <= (b); ++i)
#define REPD(i,a,b) for (int i = (a); i >= (b); --i)
#define FORI(i,n) REP(i,1,n)
#define FOR(i,n) REP(i,0,int(n)-1)
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define vi vector<int>
#define ll long long
#define SZ(x) int((x).size())
#define DBG(v) cerr << #v << " = " << (v) << endl;
#define FOREACH(i,t) for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++)
#define fi first
#define se second

const int N = 1010;

ll n, s;
int m;
pair<ll,ll> t[N];
ll a = -1;

void up(ll x) {
	if (x<1 || x>n) return;
	if (a == -1) a = x;
	if (llabs(x-s) < llabs(a-s)) {
		a = x;
	} else if (llabs(x-s) == llabs(a-s)) {
		a = min(a,x);
	}
}

int main() {
	scanf("%lld%d%lld", &n, &m, &s);
	FOR(i,m) scanf("%lld%lld", &t[i].fi, &t[i].se);
	sort(t,t+m);
	FOR(i,m) {
		if (i==0 || t[i-1].se < t[i].fi-1) up(t[i].fi-1);
		if (i==m-1 || t[i+1].fi > t[i].se+1) up(t[i].se+1);
	}
	printf("%lld\n", a);
	return 0;
}