#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll, ll>
#define pii pair<int, int>
#define fs first
#define sc second
#define pb push_back
void solve() {
int n,p,q;
cin>>n>>p>>q;
int a[n+1];
for(int i=1;i<=n;i++)cin>>a[i];
sort(a+1,a+n+1);
p=min(p,n);
int l=1,r=1e9;
while(l<r){
int m=(l+r)/2;
int dp[n+1][p+1];
memset(dp,0,sizeof(dp));
int i1=1,i2=1;
for(int i=1;i<=n;i++){
while(a[i]-a[i1]+1>m)i1++;
while(a[i]-a[i2]+1>2*m)i2++;
for(int j=0;j<=p;j++){
dp[i][j]=dp[i2-1][j]+1;
if(j)dp[i][j]=min(dp[i][j],dp[i1-1][j-1]);
}
}
if(dp[n][p]<=q)r=m;
else l=m+1;
}
cout<<l<<'\n';
}
int main() {
#ifdef FPO
freopen("in","r",stdin);
freopen("out","w",stdout);
#endif
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
solve();
}
