#define POI <cstdio>

#define Poi 0

#define poooi main()

#define poi int

#define poipoi ,

#define poipoipoi ;

#define poipoipoipoi

#define poipoipoipoipoi scanf

#define poipoipoipoipoipoi printf

#define poipoipoipoipoipoipoi return

#define poipoipoipoipoipoipoipoi "%d%d"

#define poipoipoipoipoipoipoipoipoi "%d"

#define poipoipoipoipoipoipoipoipoipoi (

#define poipoipoipoipoipoipoipoipoipoipoi )

#define poipoipoipoipoipoipoipoipoipoipoipoi +

#define poipoipoipoipoipoipoipoipoipoipoipoipoi &

#define poipoipoipoipoipoipoipoipoipoipoipoipoipoi a

#define poipoipoipoipoipoipoipoipoipoipoipoipoipoipoi b

#define poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi {

#define poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi }

#define poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi using

#define poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi namespace

#define poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi std

#include POI

poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoi

poi

poipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoi

poipoipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoi

poi

poooi

poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoi

poipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoi

poipoi

poipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoi

poipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoipoi

poipoipoi

poipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoi

poipoi

poipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoipoipoipoipoipoi

poipoipoipoipoipoipoipoipoipoipoi

poipoipoi

poipoipoipoipoipoipoi

Poi

poipoipoi

poipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoipoi

#include<cstdio>
int pre[2000],sum[2000],next[2000],mis[200];
int x,n,t,m,y,k,a,b;
bool pd[200];
bool aa,bb;
int ax,ay,az,bx,by,bz,cx,cy,cz;
int max(int a,int b,int c=-100)
{
if(a>=b && a>=c) return a;
if(b>=a && b>=c) return b;
return c;
}
void swap()
{
if(x>y) {int p=x;x=y;y=p;}
}
void build(int i,int l,int r)
{
if (l==r) {int p;scanf("%d",&p);sum[i]=pre[i]=mis[i]=next[i]=p;return;}
int mid=l+r>>1;
build(i<<1,l,mid);
build(i<<1|1,mid+1,r);
mis[i]=max(mis[i<<1],mis[i<<1|1],next[i<<1]+pre[i<<1|1]);
pre[i]=max(pre[i<<1],sum[i<<1]+pre[i<<1|1]);
next[i]=max(next[i<<1|1],next[i<<1]+sum[i<<1|1]);
sum[i]=sum[i<<1]+sum[i<<1|1];
}
void change(int i,int x,int z,int l,int r)
{
if(l==r){pre[i]=mis[i]=next[i]=sum[i]=z;return;}
int mid=l+r>>1;
if(x<=mid) change(i<<1,x,z,l,mid);
else change(i<<1|1,x,z,mid+1,r);
mis[i]=max(mis[i<<1],mis[i<<1|1],next[i<<1]+pre[i<<1|1]);
pre[i]=max(pre[i<<1],sum[i<<1]+pre[i<<1|1]);
next[i]=max(next[i<<1|1],next[i<<1]+sum[i<<1|1]);
sum[i]=sum[i<<1]+sum[i<<1|1];
}
void query(int i,int x,int y,int l,int r)
{
if(x<=l && r<=y)
{
if(!t) {ax=mis[i];bz=next[i];}
else {bx=mis[i];by=pre[i];bz=next[i];}
cx=max(ax,bx,az+by);
cz=max(bz,sum[i]+az);
cx=max(cx,cz);
ax=cx;
az=cz;
t++;
return;
}
int mid=l+r>>1;
if(x<=mid) query(i<<1,x,y,l,mid);
if(y>mid) query(i<<1|1,x,y,mid+1,r);
}
int main()
{
build(1,1,2);
query(1,1,2,1,2);
printf("%d",mis[1]);
}

#include <iostream>
using namespace std;
int main()
{
int a, b;
cin >> a >> b;
cout << a + b << endl;
return 0;
}

难度为9也，最难的题目了，我这个蒟蒻做不出来呢。。
大神们求教：
#include<iostream>
using namespace std;
int main()
{
int a,b;
cin>>a>>b;
cout<<a+b;
return 0
}
为什么没有错？

#include <stdio.h>
int main()
{
int a, b;
scanf("%d%d", &a, &b);
printf("%d\n", a + b);
return 0;
}

###Plus A+B
#include <stdio.h>
int main()
{
int a,b;
scanf("%d%d",&a,&b);
printf("%d",a+b);
return 0;
}

program Plus;
var a,b:longint;
begin
readln(a,b);
writeln(a+b);
end.

var
a,b:integer;
begin
rea(a,b);
writeln(a+b);
end.

123 500

var x,y,z:integer;
begin
readln(x,y);
z:=x+y;
write(z);
end.

var a,b,c:longint;
begin
read(a,b);
c:=a+b;
writeln(c);
end.

#include<iostream>
using namespace std;
int main(){
int a,b;
cin>>a>>b;
cout<<a+b;
return 0;
}

var
a,b:longint;
begin
read(a,b);
write(a+b);
end.

var a,b:longint;
begin
read(a,b);
writeln(a+b);
end.

Block code

水题
var
i,s,a,b:longint;
begin
readln(a,b);
s:=0;
for i:=1 to a do
inc(s);
for j:=1 to b do
inc(s);
write(s);
end.

include <stdio.h>

int main()
{
int a,b;
long c;
scanf("%d%d",&a,&b);
c=a+b;
printf("%ld",c);
return 0;
}

sdf

program aaa;
var
p,a,b:longint;
begin
randomize;
readln(a,b);
p:=random(100);
if p<=60 then
writeln(a+b);
end.

var a,b:longint;
begin
readln(a,b,);
writeln(a+b);
end.

program p1000;
var
a,b:longint;
begin
readln(a,b);
writeln(a+b);
end.