#include <fstream>
#include <queue>
#include <algorithm>
using namespace std;
ifstream fin ("timbre.in");
ofstream fout("timbre.out");
int n,m,k,x,stare,y,c,sol,i,j,l,nr,cost,T[100003],S[100003];
priority_queue <pair<int,int>> Q;
int get_root(int x)
{
    int c=x;
    while(T[x]!=x)
        x=T[x];
    int nod=c;
    while(nod!=x)
    {
        c=T[nod];
        T[nod]=x;
        nod=c;
    }
    return x;
}
void join(int x,int y)
{
    int root_a=get_root(x);
    int root_b=get_root(y);
    if(root_a<root_b)
        swap(root_a,root_b);
    T[root_b]=root_a;
}
int main()
{
    fin>>n>>m>>k;
    for(i=0;i<=n+1;i++)
        T[i]=i;
    for(i=1;i<=n;i++)
    {
        fin>>y>>cost;
        Q.push({cost,y});
    }
    j=k;
    l=m/k+1;
    for(i=m;i>=0;i--,j--)
    {
        if(!j)
        {
            j=k;
            l--;
        }
        S[i]=l;
    }

    while(nr<m/k+1)
    {
        x=Q.top().first;
        stare=S[Q.top().second];
        Q.pop();
        j=get_root(stare);
        if(j<=m/k+1)
        {
            sol+=x;
            nr++;
            //fout<<stare<<" "<<j<<"\n";
            join(j,j+1);
        }
    }
    fout<<sol<<"\n";
    return 0;
}