#include<cstdio>

#include<cstring>

#include<iostream>

#include<algorithm>

using namespace std;

#define N 500001

typedef long long LL;

int n,r;

LL k;

LL sum[N];

LL cf[N];

template<typename T>

void read(T &x)

{

    x=; char c=getchar();

    while(!isdigit(c)) c=getchar();

    while(isdigit(c)) { x=x*+c-''; c=getchar(); }

}

bool check(LL x)

{

    LL rest=k,need;

    LL add=;

    memset(cf,,sizeof(cf));

    for(int i=;i<=n;++i)

    {

        add+=cf[i];

        if(sum[i]+add<x)

        {

            need=x-sum[i]-add;

            rest-=need;

            if(rest<) return false;

            cf[i+]+=need;

            if(i+*r<n) cf[i+*r+]-=need;

        }

    }

    return true;

}

int main()

{

    read(n); read(r); read(k);

    int x;

    for(int i=;i<=n;++i)

    {

        read(x);

        sum[max(,i-r)]+=x;

        if(i+r<n) sum[i+r+]-=x;

    }

    for(int i=;i<=n;++i) sum[i]+=sum[i-];

    LL l=,r=2e18,mid,ans=;

    while(l<=r)

    {

        mid=l+r>>;

        if(check(mid)) ans=mid,l=mid+;

        else r=mid-;

    }

    cout<<ans;

}