#include <fstream>
using namespace std;
ifstream in("rucsac.in");
ofstream out("rucsac.out");
const int N=5001, K=101;
int g[N], p[N], prf[K], n, k;
int main (){
	
	in>>n;
	for(int i=1; i<=n; i++)
		in>>p[i]>>g[i];
	in>>k;
	
	for(int j=1; j<=k; j++)
 		prf[j]=-1;
	prf[0]=0;
	
	for(int i=1; i<=n; i++)
	{
		for (int j=k-g[i]; j>=0; j--)
			if(prf[j]!=-1 && prf[j]+p[i]>prf[j+g[i]])
				prf[j+g[i]]=prf[j]+prf[i];
	}
	int max=-1;
	for(int j = 1; j<=k; j++)
		if(prf[j]>max)
			max=prf[j];
		out<<max;
		return 0;
}