#include <bits/stdc++.h>
#define ll long long
using namespace std;
multiset < pair < int, int > > x;
vector < pair < int, int > > v;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n, m, s;
cin >> n >> m >> s;
for (int k=1; k<=n; k++) {
int f, s;
cin >> f >> s;
v.push_back({f,s});
x.insert({(s-f),s});
}
sort(v.begin(),v.end());
reverse(v.begin(),v.end());
ll ans=0;
for (int k=0; k<n; k++) {
if (s==0 && m==0) break;
if (s==0) {
ans+=v[k].first;
m--;
continue;
}
if (m==0) {
while (s) {
ans+=(*x.begin()).second;
s--;
x.erase(x.begin());
}
continue;
}
pair < int, int > p=(*x.begin());
if (p.first==-v[k].first+v[k].second && p.second==v[k].second) {
ans+=v[k].second;
s--;
x.erase(x.begin());
} else {
ans+=v[k].first;
m--;
}
}
cout << ans;
return 0;
}
