#include<fstream>
#include<algorithm>
using namespace std;
ifstream f("peste.in");
ofstream g("peste.out");
int n,tp,i,m,s,j,ok,jult;
struct plase
{
    int x,y;
}a[50001];
int cmp(plase a,plase b)
{
    if(a.x!=b.x)
    return a.x>b.x;
    else
    return a.y>b.y;
}
int cmp2(plase a,plase b)
{
    if(a.y!=b.y)
    return a.y>b.y;
    else
    return a.x>b.x;
}
int main()
{
    f>>n>>m>>tp;
    for(i=1;i<=n;i++)
    f>>a[i].x>>a[i].y;
    sort(a+1,a+n+1,cmp);
    for(i=1;i<=n;i++)
    {
        if(a[i].y>tp)
        {
            for(j=i;j<n;j++)
            {
                a[j].x=a[j+1].x;
                a[j].y=a[j+1].y;
            }
            n--;
        }
    }
    for(i=1;i<=m;i++)
    sort(a+1,a+n+1,cmp2);
    while(a[m].y<=tp)
    {
        for(i=1;i<=m;i++)
        s+=a[i].x;
        ok=0;
        for(j=1;j<=m&&ok==0;j++)
        {
            if(a[j].y<=tp)
            ok=1;
        }
        tp-=a[j].y;
    }
    g<<s;
    return 0;
}