#include<bits/stdc++.h>
using namespace std;
int a[114514],b1[114514],b0[114514];
int sum1=0,sum0=0; 
string s;

int main()
{
	cin>>s;
	int maxx=-114514;
	for(int i=0;i<s.length();i++)	
	{
		if(s[i]=='1')
		{
			a[i]=1;
			sum1++;
		}
		else
		{
			a[i]=0;
			sum0++;
		}
		b1[i]=sum1;
		b0[i]=sum0;
	}
	for(int i=0;i<s.length()-1;i++)//左箭头 
	{
		for(int j=i+1;j<s.length();j++)//右箭头 
		{
			maxx=max((b0[j]-b0[i])-(b1[j]-b1[i]),maxx);
		}
	}
	cout<<maxx;
 } 

测试结果：4-AC 1-WA 5-TLE