#include <stdio.h>
using namespace std;

#define Nmax 100005

int n, solution, sir[Nmax];
char c[Nmax];

void read(){
    int x;
    scanf("%i", &n);
    fgets(c+1, Nmax, stdin);
    fgets(c+1, Nmax, stdin);

    for(int i = 1, j = 1; i <= n; ++i){
        x = 0;
        while(c[j] >= '1' && c[j] <= '9') x = x * 10 + c[j++] - '0';
        ++j;
        sir[i] = x;
    }

    fclose(stdin);
}

void solve(){
    int k1, k2, sum;
    for(int i = 1; i < n; ++i){
        ++solution;
        sum = sir[i] + sir[i+1];
        for(k1 = i-1, k2 = i+2; k1 >= 1 && k2 <= n; --k1, ++k2)
            if(sir[k1] + sir[k2] == sum) ++solution;
    }
}

int main(){
    freopen("numarare.in", "r", stdin);
    freopen("numarare.out", "w", stdout);

    read();
    solve();

    printf("%i\n", solution);
    fclose(stdout);

    return 0;
}