区间DP模板题
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
inline ll read(){
ll x=0,f=1;
char ch=getchar();
while(ch<'0'||ch>'9'){
if(ch=='-')
f=-1;
ch=getchar();
}
while(ch>='0'&&ch<='9'){
x=(x<<1)+