#include<bits/stdc++.h>
using namespace std;
const int maxn=2e5+25;
#define ll long long int
#define INF 0x3f3f3f3f
int n;
int a[maxn];
ll sum[maxn];
ll b[5];
int main()
{
    int n;
    scanf("%d",&n);
    memset(sum,0,sizeof sum);
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
        sum[i]=sum[i-1]+a[i];
    }
    ll ans=-1;
    for(int i=2;i<=n-1;i++){
        ll s1=sum[i];
        ll s2=sum[n]-sum[i];
        ll x1,x2,y1,y2;
        ll av1=s1/2;ll av2=s2/2;
        // 1.0
        x1=lower_bound(sum+1,sum+i+1,av1)-sum;
        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;
       // cout<<x1<<" "<<y1<<endl;
        b[1]=sum[x1];
        b[2]=s1-sum[x1];
        b[3]=sum[y1]-s1;
        b[4]=s2-b[3];
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        sort(b+1,b+5);
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        if(ans==-1){
            ans=abs(b[4]-b[1]);
        }
        ans=min(ans,abs(b[4]-b[1]));
        //cout<<ans<<endl;


        x1=lower_bound(sum+1,sum+i+1,av1)-sum;
        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;
       // cout<<x1<<" "<<y1<<endl;
        x1--;y1--;
        b[1]=sum[x1];
        b[2]=s1-sum[x1];
        b[3]=sum[y1]-s1;
        b[4]=s2-b[3];
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        sort(b+1,b+5);
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        if(ans==-1){
            ans=abs(b[4]-b[1]);
        }
        ans=min(ans,abs(b[4]-b[1]));



        x1=lower_bound(sum+1,sum+i+1,av1)-sum;
        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;
       // cout<<x1<<" "<<y1<<endl;
        x1--;
        b[1]=sum[x1];
        b[2]=s1-sum[x1];
        b[3]=sum[y1]-s1;
        b[4]=s2-b[3];
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        sort(b+1,b+5);
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        if(ans==-1){
            ans=abs(b[4]-b[1]);
        }
        ans=min(ans,abs(b[4]-b[1]));


        x1=lower_bound(sum+1,sum+i+1,av1)-sum;
        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;
       // cout<<x1<<" "<<y1<<endl;
        y1--;
        b[1]=sum[x1];
        b[2]=s1-sum[x1];
        b[3]=sum[y1]-s1;
        b[4]=s2-b[3];
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        sort(b+1,b+5);
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        if(ans==-1){
            ans=abs(b[4]-b[1]);
        }
        ans=min(ans,abs(b[4]-b[1]));

        //2.0
        av1=s1/2;av2=s2/2;
        x1=upper_bound(sum+1,sum+i+1,av1)-sum;
        y1=lower_bound(sum+i+2,sum+1+n,s1+av2)-sum;
       // cout<<x1<<" "<<y1<<endl;
        b[1]=sum[x1];
        b[2]=s1-sum[x1];
        b[3]=sum[y1]-s1;
        b[4]=s2-b[3];
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        sort(b+1,b+5);
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        if(ans==-1){
            ans=abs(b[4]-b[1]);
        }
        ans=min(ans,abs(b[4]-b[1]));

        //3.0
        av1=s1/2;av2=s2/2;
        x1=lower_bound(sum+1,sum+i+1,av1)-sum;
        y1=upper_bound(sum+i+2,sum+1+n,s1+av2)-sum;
       // cout<<x1<<" "<<y1<<endl;
        b[1]=sum[x1];
        b[2]=s1-sum[x1];
        b[3]=sum[y1]-s1;
        b[4]=s2-b[3];
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        sort(b+1,b+5);
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        if(ans==-1){
            ans=abs(b[4]-b[1]);
        }
        ans=min(ans,abs(b[4]-b[1]));

        //4.0
        av1=s1/2;av2=s2/2;
        x1=upper_bound(sum+1,sum+i+1,av1)-sum;
        y1=upper_bound(sum+i+2,sum+1+n,s1+av2)-sum;
       // cout<<x1<<" "<<y1<<endl;
        b[1]=sum[x1];
        b[2]=s1-sum[x1];
        b[3]=sum[y1]-s1;
        b[4]=s2-b[3];
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        sort(b+1,b+5);
        //cout<<b[1]<<" "<<b[2]<<" "<<b[3]<<" "<<b[4]<<endl;
        if(ans==-1){
            ans=abs(b[4]-b[1]);
        }
        ans=min(ans,abs(b[4]-b[1]));

    }
    printf("%lld\n",ans);
    return 0;
}


Measured memory_bytes: 2560