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#include<bits/stdc++.h>
using namespace std;
using ll=long long;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	ll n;
	int m;
	ll s;
	cin>>n>>m>>s;
	map<ll,int> ban;
	vector<ll> vec={1,n};
	for(int i=1;i<=m;i++)
	{
		ll l,r;
		cin>>l>>r;
		if(l!=1)
			vec.push_back(l-1);
		if(r!=n)
			vec.push_back(r+1);
		ban[l]=ban[r]=1;
	}
	ll ans=-1;
	for(auto pos:vec)
		if(!ban[pos])
		{
			if(ans==-1) ans=pos;
			else if(abs(pos-s)<abs(ans-s))
				ans=pos;
			else if(abs(pos-s)==abs(ans-s)&&pos<ans)
				ans=pos;
		}
	cout<<ans<<'\n';
	return 0;
}