Hack？？？？？

#include<bits/stdc++.h>
using namespace std;
int s,n,m,ans;
int a[50005];
bool ck(int x){
	int sum=0;
	int b[50005];
	for(int i=0;i<=n+1;i++)b[i]=a[i];
	for(int i=1;i<=n;i++){
		if(b[i]-b[i-1]<x){
			sum++;
			b[i]=b[i-1];
		}
	}
	if(b[n+1]-b[n]>=x){
		return sum<=m;
	}else{
		return 0;
	}
}
int main(){
	cin>>s>>n>>m;
	for(int i=1;i<=n;i++)cin>>a[i];
	a[n+1]=s;
	int l=1,r=1e9;
	while(l<=r){
		int mid=l+(r-l)/2;
		if(ck(mid)){
			ans=mid;
			l=mid+1;
		}else{
			r=mid-1;
		}
	}
	cout<<ans;
}