p2678求调 全WA

#include<iostream>
using namespace std;
int l,n,m;
int a[1000005],ms[1000005];
int le=1,ri=l;
int main(){
	cin>>l>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		ms[i]=a[i]-a[i-1];
	} 
	a[n+1]=l;
	while(le<=ri){
		int cnt;
		int mid=(le+ri)>>1;
		for(int i=1;i<=n;i++){
			if(ms[i]<mid) cnt++,ms[i+1]+=ms[i];
			else continue;
		}
		if(cnt>m) le=mid+1;
		else ri=mid-1;
	}
	cout<<le;
	return 0;
}