#include <stdio.h>
#include <algorithm>
using namespace std;

long t, i, j, n, k, a, b, nx;

struct lol
{
       long a, b;
       double c;
};
lol x[50010];

int cmpf(lol a, lol b)
{
    return a.c > b.c;
}

long abss(long a)
{
     return a < 0 ? -a : a;
}

long valid(long rez)
{
     long i, j, sum = 0, kc, tc = t;
     while (tc && sum < rez)
     {
           i = 1;
           while (tc < x[i].b && i <= n + 1)
                 ++i;
           if (i == n + 1)
              return sum >= rez;

           kc = 1;
           sum += x[i].a;
           for (j = i + 1; j <= n && kc < k; j ++)
               if (x[j].b <= x[i].b)
               {
                          kc ++;
                          sum += x[j].a;
               }
      
           tc -= x[i].b;
     }
     
     return sum >= rez;
}

long cautbin(long st, long dr)
{
     long m = (st + dr) / 2;
     if (abss(st - dr) <= 1)
        return valid(dr) ? dr : st;
     if (valid(m))
        return cautbin(m, dr);
     return cautbin(st, m - 1);
}

int main()
{
    freopen ("peste.in", "rt", stdin);
    freopen ("peste.out", "wt", stdout);
    
    scanf("%ld %ld %ld", &n, &k, &t);
    
    for (i = 1; i <= n; ++i)
    {
        scanf("%ld %ld", &a, &b); 
        if (b <= t)
        { 
              x[++nx].a = a;
              x[nx].b = b;
              x[nx].c = (double) x[nx].a / x[nx].b;
        }
    }
    n = nx;
    
    sort(x + 1, x + n + 1, cmpf);
    
    printf("%ld\n", cautbin(0, 500000000));
    
    return 0;
}