#include<bits/stdc++.h>
using namespace std;
#define ll long long
inline ll read(){
   ll s=0,w=1;
   char ch=getchar();
   while(ch<'0'||ch>'9'){if(ch=='-')w=-1;ch=getchar();}
   while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
   return s*w;
}
pair<ll,ll> a[1<<20],ans={1ll<<60,-1};
signed main()
{
	ll n=read(),m=read(),s=read();
	for(int i=1; i<=m; ++i)
		a[i].first=read(),
		a[i].second=read();
	sort(a+1,a+m+1),
	a[0]={0,0},a[m+1]={n+1,n+1};
	for(int i=0; i<=m; ++i)
	{
		ll l=a[i].second+1;
		ll r=a[i+1].first-1;
		if(l<=r)
			ans=min(ans,{abs(l-s),l}),
			ans=min(ans,{abs(r-s),r});
	}
	printf("%lld\n",ans.second);
	return 0;
}