#include<stdio.h>
#include<vector>
#define inf 100000000
using namespace std;
long n, k, i;
long x, min1, sum, val;
vector <long> v;
void find_minim()
{
    min1=inf;
    for(int j=1;j<v.size();j++)
        if(min1>v[j])
            min1=v[j];
}
int main()
{
    freopen("deque.in","r",stdin);
    freopen("deque.out","w",stdout);
    scanf("%ld %ld",&n,&k);
    min1=inf;
    for(i=0;i<k;i++)
    {
        scanf("%ld",&x);
        v.push_back(x);
        if(x<min1)
            min1=x;
    }
    sum+=min1;
    for(i=k;i<n;i++)
    {
        scanf("%ld",&x);
        v.push_back(x);
        if(min1>x)
            min1=x;
        if(min1==*v.begin())
            find_minim();
        sum+=min1;
        v.erase(v.begin());
    }
    printf("%ld",sum);
    return 0;
}