#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ar array
#define fr first
#define sc second
#define vec vector
#define ret return
#define ins insert
#define mk make_pair
#define pb push_back
#define pf push_front
#define pob pop_back
#define pof pop_front
#define int long long
#define pii pair<int,int>
#define all(s) s.begin(), s.end()
#define allr(s) s.rbegin(), s.rend()
#define NeedForSpeed ios::sync_with_stdio(0),cin.tie(0);
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
const int N=1e6+12,INF=1e9,mod = 1e9+7;
bool iswowel(char n){ n = toupper(n); if(n == 'A' || n == 'O' || n == 'U' || n == 'E' || n == 'I') return true; else return false;}
int n,m,k,l,r,o,ans,res,ok,mx,mn = INF;
vec<pair<int, pii>>v;
main(){
NeedForSpeed
int x, y;
cin>>n>>x>>y;
for(int i=1; i<=n; i++){
cin>>l>>r;
v.pb(mk(l-r, mk(l, r)));
}
sort(all(v));
multiset<pair<int, pii>>t;
multiset<pii>s, p;
l = 0;
for(int i=0; i<y; i++){
s.ins({v[i].sc.fr, v[i].sc.sc});
l += v[i].sc.sc;
}
for(int i=y; i<n; i++){
t.ins(v[i]);
p.ins({v[i].sc.fr, v[i].sc.sc});
}
for(int i=y; i<n-x+1; i++){
auto it = p.end();
o = x,r = 0;
while(o--){
it--;
r += (it->fr);
}
res = max(res, l + r);
l += t.begin()->sc.sc;
s.ins({t.begin()->sc.fr, t.begin()->sc.sc});
p.erase(p.find({t.begin()->sc.fr, t.begin()->sc.sc}));
while(s.size() > y){
l -= s.begin()->sc;
s.erase(s.begin());
}
t.erase(t.begin());
}
cout<<res<<endl;
return 0;
}
