#include<fstream>
#include<cstring>
#include<queue>
#include<algorithm>
#include<string.h>
#include<bitset>
#include<ctime>
#include<set>
#include<cmath>
#include<unordered_map>
#include<iomanip>
#include<map>
#include<stack>
#include<vector>
#include<bitset>
#include<functional>
#include<iostream>
#include<deque>
#include<unordered_set>
#include<queue>
#include<list>
#include<array>
#include<ctype.h>
using namespace std;
long long i, j, k, ok, nr, n, m, el, min1, max1, x, y, a, b,v[2000100],sum,dp[2000100],w,rez,X;
int main()
{
	cin >> n>>X>>k;
	for (i = 1; i <= n; i++)
	{
		cin >> x >> w;
		v[x + 1000000] = w;
	}
	for (i = 0; i <= 2000000; i++)
		if(i!=0)
			dp[i] = dp[i - 1] + v[i];
	for (i = 1000000+X; i <= 1000000+X+k; i++)
	{
		rez=max(rez,dp[i] - dp[i-k]);
	}
	cout << rez;
	return 0;
}