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#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=(a);i<(n);i++)
#define per(i,a,n) for (int i=(n)-1;i>=(a);i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(1111); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

int m;
ll n,s;
vector<pair<ll,ll>> p,q;
int main() {
	scanf("%lld%d%lld",&n,&m,&s);
	rep(i,0,m) {
		ll l,r;
		scanf("%lld%lld",&l,&r);
		p.pb(mp(l,r));
	}
	sort(all(p));
	rep(i,0,SZ(p)) {
		if (q.empty()||q.back().se+1!=p[i].fi) {
			q.pb(p[i]);
		} else {
			q.back().se=p[i].se;
		}
	}
	ll ans=-1;
	for (auto [l,r]:q) if (s>=l&&s<=r) {
		if (l>1) ans=l-1;
		if (ans==-1||(r+1<=n&&r+1-s<s-ans)) ans=r+1;
	}
	printf("%lld\n",ans);
}