#include<iostream>
#include<cmath>
#include<algorithm>
using namespace std;
const int N=200001;
long long ans;
long long consume[N],color[N],f[N],color_n[51],color_n_ok[51];
int main()
{
    int n,m,p;
    cin>>n>>m>>p;
    for(int i=1;i<=n;i++) cin>>color[i]>>consume[i];
    for(int i=1;i<=n;i++)
		if(consume[i]<=p)
		{
			f[i]=color_n[color[i]]++;
			copy(color_n,color_n+m+1,color_n_ok);		
		}  
		else
		{
			f[i]=color_n_ok[color[i]];
			color_n[color[i]]++;	
		}
		
		for(int i=1;i<=n;i++)	ans+=f[i];
		cout<<ans<<endl;
		
		return 0;
}
/**************************************************************
	Problem: 2305
	User: admin
	Language: C++
	Result: Accepted
	Time:246 ms
	Memory:6760 kb
****************************************************************/