#include <bits/stdc++.h>
using namespace std;
int shuzu[100001];
char abcdefg[100001];
int Man=-2147483648;
int main(){
    cin>>abcdefg;
    for(int i=0;i<strlen(abcdefg);i++){
        int shu;
        if(abcdefg[i]=='0'){
            shu=1;
        }else{
            shu=-1;
        }
        shuzu[i+1]=shuzu[i]+shu;
    }
    for(int i=1;i<=strlen(abcdefg);i++){
        for(int j=i;j<=strlen(abcdefg);j++){
            Man=max(Man,shuzu[j]-shuzu[i-1]);
        }
    }
    cout <<Man;
    return 0;
}