#include<cstdio>
#include<algorithm>
using namespace std;

struct node
{
    int times,money;
}a[105];

bool cmp(node x,node y)
{
    return x.money+x.times < y.money+y.times;
}

int main()
{
    int n,m,t;
    scanf("%d%d%d",&n,&m,&t);
    for(int i=1;i<=n;i++)
        scanf("%d%d",&a[i].times,&a[i].money);
    sort(a+1,a+n+1,cmp);
    int i=1,ans=0;
    while(m&&t)
    {
        if(a[i].money!=0)
        {
            a[i].money--;
            m--;
            if(a[i].times!=0)
            {
                a[i].times--;
                t--;
            }
        }
        else
        {
            i++;
            ans++;
        }
    }
    printf("%d\n",ans);
    return 0;
}