/*
    _ 
   / \   _ __ ___  _ __ ___   __ _ _ __  __      ___ __ ___ | |_ ___ 
  / _ \ | '_ ` _ \| '_ ` _ \ / _` | '__| \ \ /\ / / '__/ _ \| __/ _ \
 / ___ \| | | | | | | | | | | (_| | |     \ V  V /| | | (_) | ||  __/
/_/   \_\_| |_| |_|_| |_| |_|\__,_|_|      \_/\_/ |_|  \___/ \__\___|
                                                                     
 _   _     _             _                        __                        
| |_| |__ (_)___   _ __ (_) ___  ___ ___    ___  / _|   ___ _ __ __ _ _ __  
| __| '_ \| / __| | '_ \| |/ _ \/ __/ _ \  / _ \| |_   / __| '__/ _` | '_ \ 
| |_| | | | \__ \ | |_) | |  __/ (_|  __/ | (_) |  _| | (__| | | (_| | |_) |
 \__|_| |_|_|___/ | .__/|_|\___|\___\___|  \___/|_|    \___|_|  \__,_| .__/ 
                  |_|                                                |_| 
*/

//https://codeforces.com/gym/102152
#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long int ull;
typedef long double ldb;

#define PB push_back
#define For(i, n) for (ll i = 0; i < n; i++)
#define trav(a,x) for (auto& a : x)
#define PYES cout<<"YES\n"
#define PNO cout<<"NO\n"
#define PYes cout<<"Yes\n"
#define PNo cout<<"No\n"

#define sq(x)           (x*x)

#define vll             vector<ll>
#define pll             pair<ll,ll>
#define ff              first
#define ss              second
#define rev(v)          reverse(v.begin(),v.end())
#define srt(v)          sort(v.begin(),v.end())
#define grtsrt(v)       sort(v.begin(),v.end(),greater<ll>())
#define mnv(v)          *min_element(v.begin(),v.end())
#define mxv(v)          *max_element(v.begin(),v.end())
#define all(v)          v.begin(),v.end()
#define ACC(v)          accumulate(v.begin(),v.end(),0ll)
#define ammario main
#define eps             1e-9

const double PI=acos(-1.0);


#define fastIO ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define fileIO freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);

mt19937 rng((unsigned int)chrono::steady_clock::now().time_since_epoch().count());

//--------------------------------------------functions-------------------------------------------------//

ll power(ll a,ll b){ll result=1;while(b>0){if(b%2 == 1){result *= a;} a *= a;b /= 2;}return result;}
ll gcd(ll x,ll y){ll r;while(y!=0&&(r=x%y)!=0){x=y;y=r;}return y==0?x:y;}
ll countSetBits(ll x){ll Count=0;while(x>0){if(x&1) Count++;x=x>>1;}return Count;}
ll mod(ll x,ll M){return ((x%M + M)%M);}
ll add(ll a, ll b,ll M){return mod(mod(a,M)+mod(b,M),M);}
ll mul(ll a, ll b,ll M){return mod(mod(a,M)*mod(b,M),M);}
ll powerM(ll a,ll b,ll M){
    ll res=1ll;
    while(b){
        if(b%2ll==1ll){
            res=mul(a,res,M);
        }
        a=mul(a,a,M);b/=2ll;
    }
    return res;
}
ll mod_inv(ll a, ll m) {
    ll g = m, r = a, x = 0, y = 1;
    while (r != 0) {
        ll q = g / r;
        g %= r; swap(g, r);
        x -= q * y; swap(x, y);
    }
    return mod(x,m);
}
////------------------------------------sieve of erantothenes-----------------------------------------------//
ll MAXN=1e6+1000;
vector<ll> fact(MAXN+1);
void sieve_of_erantothenes()
{
    fact[1] = 1;
    for (ll i = 2; i <= MAXN; i++)
        fact[i] = i;
    for (ll i = 4; i <= MAXN; i += 2)
        fact[i] = 2;
    for (ll i = 3; i * i <= MAXN; i++){
        if (fact[i] == i){
            for (ll j = i * i; j <= MAXN; j += i)
                if (fact[j] == j)
                    fact[j] = i;
        }
    }
}
//----------------------------------------nCr mod------------------------------------------------------//
ll nCr(ll n, ll k){
    if(n<k) return 0;
    if(k==0) return 1;
    ll res = 1;
    if (k > n - k) k = n - k;
    for(ll i = 0; i < k; ++i){
        res *= (n - i);
        res /= (i + 1);
    }
    return res;
}

vector<ll> FA,INV;
void fcalc(ll n,ll M){
    FA.resize(n+1);
    FA[0]=1;
    for(ll i=1;i<=n;i++){
        FA[i]=(FA[i-1]*i)%M;
    }
}

void icalc(ll n,ll M){
    INV.resize(n+1);
    INV[n]=mod_inv(FA[n],M);
    for(ll i=n-1;i>=0;i--){
        INV[i]=(INV[i+1]*(i+1))%M;
    }
}
ll nCrM(ll n,ll r,ll M){
    if(n<r) return 0;
    if(r==0) return 1;
    ll a=FA[n];
    a*=INV[r];
    a%=M;
    a*=INV[n-r];
    a%=M;
    return a;
}
ll rand_int(ll l, ll r){
    return uniform_int_distribution<ll>(l, r)(rng);
}
//--------------------------------------------main----------------------------------------------------//
void pls_werk_b0ss()
{
    ll n,k;cin>>n>>k;
    ll sum=0,ans=LONG_LONG_MAX;
    vll a(n);
    For(i,n)cin>>a[i],sum+=a[i];
	for(int i=0;i<k;i++)
    {
		ll temp=0;
		for(int j=i;j<n;j+=k)temp+=a[j];
		ans=min(ans,sum-temp);
	}
	cout<<ans<<"\n";
}
int ammario()
{
    fastIO
    int t=1;//cin>>t;
    while(t--)pls_werk_b0ss();
}