use std::fs::File;
use std::io::{*};
use std::collections::HashSet;

fn makes_square(x : &(i32, i32), y : &(i32, i32), set : &HashSet<(i32, i32)>) -> bool {
    let xmid = (x.0 + y.0) / 2;
    let ymid = (x.1 + y.1) / 2;

    let dx = xmid - x.0;
    let dy = ymid - x.1;

    let a = (xmid - dy, ymid + dx);
    let b = (xmid + dy, ymid - dx);

    if set.contains(&a) && set.contains(&b) {
        return true;
    }

    return false;
}

fn main() {
    let mut set : HashSet<(i32, i32)> = HashSet::new();
    
    let mut input = BufReader::new(File::open("patrate3.in").unwrap());
    let mut output = BufWriter::new(File::create("patrate3.out").unwrap());

    let mut line = String::new();
    input.read_line(&mut line).unwrap();
    let n : usize = line.trim().parse().unwrap();

    let mut points : Vec<(i32, i32)> = Vec::new();

    for _i in 0..n {
        let mut line = String::new();
        input.read_line(&mut line).unwrap();

        let vars : Vec<f64> = line.split(" ").map(|x| x.trim().parse().unwrap()).collect();

        let x : i32 = (vars[0] * 10000.0).round() as i32;
        let y : i32 = (vars[1] * 10000.0).round() as i32;

        points.push((x, y));
    }

    for pr in &points {
        set.insert(*pr);
    }

    let mut counter : usize = 0;

    for i in 0..n {
        for j in i+1..n {
            if i != j && makes_square(&points[i], &points[j], &set) {
                counter = counter + 1;
            }
        }
    }

    writeln!(output, "{}", counter / 2).unwrap();
}