#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<fstream>
#include<map>
#include<ctime>
#include<set>
#include<queue>
#include<cmath>
#include<vector>
#include<bitset>
#include<functional>
#define x first
#define y second
#define mp make_pair
#define pb push_back
#define REP(i,l,r) for((i)=(l);(i)<=(r);++(i))
#define REP2(i,l,r) for((i)=(l);(i)!=(r);++(i))
using namespace std;
 
typedef long long LL;
typedef double ld;
 
const int MAX=1000000+10;
 
int n;
int x[MAX];
//if x_i<0 then x_i+x_{i-1}<x_{i-1}
//最终结果一定是-1 -1 -1 -1...0 0 0 0...1 1 1 1的形式
int f[MAX][3];
 
void update(int& a,int b)
{
    if(b!=-1 && (a==-1 || b<a))
        a=b;
}
 
int main()
{
#ifndef ONLINE_JUDGE
//    freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);
#endif
    int i,j,k;
    scanf("%d",&n);
    REP(i,1,n)
        scanf("%d",&x[i]);
    memset(f,-1,sizeof f);
    f[1][x[1]+1]=0;
    for(i=2;i<=n;++i)
        REP(j,-1,1)
            if(f[i-1][j+1]!=-1)
                REP(k,0,3)
                    if(j*k+x[i]<=1 && j*k+x[i]>=j)
                        update(f[i][j*k+x[i]+1],f[i-1][j+1]+k);
    int ans=-1;
    REP(j,-1,1)
        update(ans,f[n][j+1]);
    if(ans==-1)
        printf("BRAK\n");
    else printf("%d\n",ans);
    return 0;
}
 

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NgotMSAxIDAgLTEgMCAx

6
-1 1 0 -1 0 1