#include <bits/stdc++.h>
#define ll long long
using namespace std;
struct ABC {
int fir, sec, ind;
};
bool comp (ABC a, ABC b) {
return a.fir>b.fir;
}
ABC v[300005];
pair < int, int > se[300005], fi[300005];
bool used[300005];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
ll n, m, s;
cin >> n >> m >> s;
for (int k=1; k<=n; k++) {
cin >> v[k].fir;
cin >> v[k].sec;
fi[k].first=v[k].fir;
fi[k].second=k;
se[k].first=v[k].sec;
se[k].second=k;
v[k].ind=k;
}
sort(v+1,v+1+n, comp);
int k=1; ll ans=0;
while (k<n && s && m) {
ans+=max(v[k].sec+v[k+1].fir,v[k].fir+v[k+1].sec);
used[v[k].ind]=true;
used[v[k+1].ind]=true;
m--;
s--;
k+=2;
}
if (m==0) {
sort(se+1,se+1+n);
reverse(se+1,se+1+n);
for (int i=1; i<=n; i++) {
if (s==0) break;
if (used[se[i].second]) continue;
ans+=se[i].first;
s--;
}
cout << ans;
return 0;
}
if (s==0) {
sort(fi+1,fi+1+n);
reverse(fi+1,fi+1+n);
for (int i=1; i<=n; i++) {
if (m==0) break;
if (used[fi[i].second]) continue;
ans+=fi[i].first;
m--;
}
cout << ans;
return 0;
}
return 0;
}
