#include <bits/stdc++.h>

using namespace std;
ifstream f("deque.in");
ofstream g("deque.out");
int n,i,a[1001],x[1001],b,Min,s;
deque <int> Dq;
int main()
{f >> n >> b;Min=10000000;s=0;
 for(i=1;i<=n;i++)
 f >> a[i];
 for(i=1;i<=n;i++){
 if(a[i]>a[i+1])x[i]=i;
 else Dq.pop_front();
 if(a[i]<Min)Min=a[i];
 if(i==b)s+=Min;
}
 g << s;
 return 0;
}