#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define MAXN 100010
inline ll read(){
    ll x=0,f=1;
    char ch=getchar();
    while(ch<'0'||ch>'9'){
        if(ch=='-')f=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9'){
        x=x*10+ch-'0';
        ch=getchar(); 
    }
    return x*f;
}
ll n,s,t,ans=LONG_LONG_MIN;
ll pre[MAXN];
struct node{
    ll p,w;
};
deque<node> q;
int main(){
    freopen("ggame.in","r",stdin);
    freopen("ggame.out","w",stdout);
    n=read(),s=read(),t=read();
//    cin>>n>>s>>t;
    for(int i=1;i<=n;i++){
        pre[i]=read();
//        cin>>pre[i];
        pre[i]+=pre[i-1];
        while(!q.empty()){
            if(q.front().p+t<=i)q.pop_front();
            else break;
        }
        if(i>=s){
            node now=(node){i-s+1,pre[i-s]};
            while(!q.empty()){
                if(q.back().p+t<=i||q.back().w>=now.w)q.pop_back();
                else break;
            }
            q.push_back(now);
//            cout<<i<<" "<<q.front().p<<" "<<q.front().w<<endl;
            ans=max(ans,pre[i]-q.front().w);
        }
    }
    cout<<ans;
    return 0;
}