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#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<queue>
#include<map>
#include<stack>
#include<cmath>
#include<set>
#include<bitset>
#include<complex>
#include<assert.h>
#define inc(i,l,r) for(int i=l;i<=r;i++)
#define dec(i,l,r) for(int i=l;i>=r;i--)
#define link(x) for(edge *j=h[x];j;j=j->next)
#define mem(a) memset(a,0,sizeof(a))
#define ll long long
#define eps 1e-8
#define succ(x) (1<<x)
#define lowbit(x) (x&(-x))
#define sqr(x) ((x)*(x))
#define mid (x+y)/2
#define NM 100005
#define nm 105
using namespace std;
const double pi=acos(-1);
const ll inf=998244353;
ll read(){
ll x=0,f=1;char ch=getchar();
while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
return f*x;
}
const int cnt=4000;
int n,a[NM],pre[NM],suc[NM];
ll c[NM],b[NM],ans,d[NM];
#define cp complex<double>
struct FFT{
int n,bit,rev[NM];
cp a[NM],b[NM];
void fft(cp*a,int f){
inc(i,0,n-1)if(i<rev[i])swap(a[i],a[rev[i]]);
for(int k=1;k<n;k<<=1){
cp t(cos(pi/k),f*sin(pi/k));
for(int i=0;i<n;i+=k<<1){
cp w(1,0);
for(int j=0;j<k;j++,w*=t){
cp x=a[i+j],y=w*a[i+j+k];
a[i+j]=x+y;a[i+j+k]=x-y;
}
}
}
}
int plu(ll*_a,ll*_b,int p,int m){
n=p;
inc(i,0,n)a[i]=_a[i];
inc(i,0,m)b[i]=_b[i];
for(n=m=n+m+1,bit=0;succ(bit)<n;bit++);n=succ(bit);
inc(i,0,n-1)rev[i]=(rev[i>>1]>>1)|((i&1)<<(bit-1));
fft(a,1);fft(b,1);inc(i,0,n-1)a[i]*=b[i];
fft(a,-1);inc(i,0,n-1)a[i]/=n;
inc(i,0,n-1)_a[i]=a[i].real()+0.5;
inc(i,0,n-1)a[i]=b[i]=0;
return m-1;
}
}fft;
int main(){
n=read();inc(i,1,n)a[i]=pre[i]=suc[i]=read(),b[a[i]]++;
inc(i,1,n)pre[i]=max(pre[i],pre[i-1]);
dec(i,n,1)suc[i]=max(suc[i],suc[i+1]);
for(int x=1,y=cnt;x<=n;x=y+1,y+=cnt){
y=min(y,n);
inc(i,x,y)b[a[i]]--;
inc(i,x,y){
inc(j,i+1,y){
if(2*a[i]>a[j])ans+=d[2*a[i]-a[j]],ans+=c[2*a[i]-a[j]];
if(2*a[j]>a[i])ans+=b[2*a[j]-a[i]];
}
d[a[i]]++;
}
inc(i,x,y)d[a[i]]--;
inc(i,0,suc[y+1])d[i]=b[i];
int tot=fft.plu(d,c,suc[y+1],pre[x-1]);
inc(i,x,y)ans+=d[2*a[i]];
inc(i,0,tot)d[i]=0;
inc(i,x,y)c[a[i]]++;
}
return 0*printf("%lld\n",ans);
}
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