#include <iostream>
using namespace std;
int n,k,p,ans;

struct kz{
	int color;
	int money;
}a[20000000];

int len;
int main()
{
	cin>>n>>k>>p;
	for(int i=1;i<=n;i++){
		cin>>a[i].color>>a[i].money;
		len++;
	}
	int mid=len/2;
	//cout<<len<<endl;
	for(int i=2;i<n;i++){
		int k=i;
		if(a[i].money<=p){
			if(len%2==0){
				
				if(k<=mid)ans+=k;
					else ans=ans+len-k;
			}
				else {
					if(k<mid){
						ans+=k;
					}
						else if(k==mid)ans+=mid-1;
							else ans+=len-k;
				}
			
		}
	}
	
	cout<<ans<<endl;
	
	return 0;
}