codeforces 391C3 - The Tournament

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 200009
#define inf 1e15
using namespace std;
int n,k,q;
struct node
{
    int score;
    int pain;
    bool operator<(const node &t)const
    {
        return pain<t.pain;
    }
} no[maxn];

bool cmp(const node &a,const node &b)
{
    return a.score>b.score;
}

bool vis[maxn];
int s[maxn];

long long check(int p)
{
    long long ans=0;
    int cnt_1=0;
    for(int i=1;i<=n;i++)
        if(no[i].score>=p-1)cnt_1++;
    cnt_1-=k-1;
    int cnt_2=0;
    for(int i=1;i<=n&&cnt_2<cnt_1;i++)
    {
        if(no[i].score==p||no[i].score==(p-1))
        {
            ans+=no[i].pain;
            cnt_2++;
            vis[i]=1;
        }
    }
    for(int i=1;i<=n&&cnt_2<p;i++)
    {
        if(!vis[i])
        {
            ans+=no[i].pain;
            cnt_2++;
        }
    }
    memset(vis,0,sizeof vis);
    return ans;
}

int main()
{
    scanf("%d%d",&n,&k);
    for(int i=1; i<=n; i++)
        scanf("%d%d",&no[i].score,&no[i].pain);
    sort(no+1,no+n+1,cmp);
    int tar=no[k].score;
    sort(no+1,no+n+1);
    long long ans=inf;
    for(int i=tar;i<=tar+2;i++)
    {
        if(i>n)break;
        ans=min(ans,check(i));
    }
    if(ans==inf)ans=-1;
    cout<<ans<<endl;;
}