1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
#include <bits/stdc++.h>

#define ll long long
#define ld long double
#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
using namespace std;
int inf=1000000007;
ll infl=1000000000000000007;
ll mod=1000000007;
ll mod1=998244353;

const int N=507,S=20007;
const int T=3*N*S;

int ile[N*S*6];

int a[N];
int p[N];

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
	int n;
	cin>>n;
	ll ans=0;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
		p[i]=p[i-1]+a[i];
	}
	//aaa
	for(int i=1;i<=n;i++)
	{
		ile[3*p[i-1]+T]++;
		for(int j=i+1;j<=n;j++)
		{
			for(int l=j+1;l<=n;l++)
			{
				ans+=ile[(p[i]+p[j]+p[l])+T];
			}
		}
	}
	memset(ile,0,sizeof ile);
    //aa<b
    for(int i=1;i<=n;i++)
	{
		for(int j=i;j<=n;j++)
		{
			for(int l=j+1;l<=n;l++)
			{
				ile[2*p[i-1]-p[j]-p[l]+T]++;
			}
		}
		for(int j=i+1;j<=n;j++) 
		{
			ans+=ile[-(p[i]-p[j])+T];
		}
	}
    memset(ile,0,sizeof ile);
    //a<bb
    for(int i=1;i<=n;i++)
    {
		for(int j=i;j<=n;j++) ile[p[i-1]-p[j]+T]++;
		for(int j=i+1;j<=n;j++)
		{
			for(int l=j+1;l<=n;l++)
			{
				ans+=ile[-(2*p[i]-p[j]-p[l])+T];
			}
		}
	}
	memset(ile,0,sizeof ile);
    //a<b<c
    for(int i=1;i<=n;i++)
    {
		for(int j=i-2;j>=0;j--)
		{
			for(int l=j+1;l<=n;l++)
			{
				ile[p[i-1]+p[j]-p[l]+T]++;
			}
		}
		//c>=y
		for(int j=i;j<=n;j++)
		{
			for(int l=j+1;l<=n;l++)
			{
				ans+=ile[-(p[j]-p[i]-p[l])+T];
			}
		}	
		//c<y
		for(int j=i+1;j<=n;j++)
		{
			for(int l=i+1;l<=n;l++)
			{
				ans+=ile[-(p[i]-p[j]-p[l])+T];
			}
		}
	}
	cout<<ans;
    return 0;
}