为什么最后一个点会wa！！！

#include<bits/stdc++.h>
#define LL long long
using namespace std;
LL l1,n,m,a[50010],ans,maxn=INT_MIN;

int check(int tmp){
	int lt=1,q=0;
	for (int i=1;i<=n;i++){
		if (a[i]-lt>=tmp)q++,lt=a[i];
	}
	if (n-q<=m)return 0;
	else return 1;
} 
int main(){
	cin>>l1>>n>>m;
	for (int i=1;i<=n;i++){
		 cin>>a[i];
		 maxn=max(maxn,a[i]);
	}
	int r=l1,l=1;
	while (l<=r){
		int mid=(r+l)/2;
		if (check(mid)==0){
			ans=mid;
			l=mid+1;
		}else r=mid-1;
	}
	cout<<ans;
	return 0;
}