#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
typedef long long ll;
int N,M,S;
ll d[501][101][101];
ll a[501],b[501];
ll f(int p,int x,int y){
if(p==N){
if(x<M||y<S)return -1e18;
return 0;
}
if(x==M&&y==S)return f(p+1,x,y);
if(x==M)return f(p+1,x,y+1)+b[y];
if(y==S)return f(p+1,x+1,y)+a[x];
ll& ret=d[p][x][y];
if(~ret)return ret;
return ret=max(f(p+1,x+1,y)+a[x],f(p+1,x,y+1)+b[y]);
}
int main(){
scanf("%d%d%d",&N,&M,&S);
for(int i=0;i<N;i++){
scanf("%lld%lld\n",&a[i],&b[i]);
}
memset(d,-1,sizeof(d));
printf("%lld\n",f(0,0,0));
return 0;
}
