#include<iostream>
#include<stdio.h>
#define min(a,b) a<b?a:b
using namespace std;

struct aaa
{
	int k[51];
}t[200001];

int n,k,p,a[200001],b[200001];

long long ans;

int main()
{
	freopen("hotel.in","r",stdin);
	freopen("hotel.out","w",stdout);
	int i,j,tmp;
	scanf("%d%d%d",&n,&k,&p);
	tmp=0;
	for(i=1;i<=n;i++)
	{
		scanf("%d%d",&a[i],&b[i]);
		t[i]=t[i-1];
		if(b[i]<=p)
		{
			tmp=i;
		}
		ans+=t[tmp].k[a[i]];
		t[i].k[a[i]]++;
	}
	cout<<ans<<endl;
	fclose(stdin);
	fclose(stdout);
	return 0;
}