[HDOJ5365]Run

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <cmath>
#include <cctype>
#include <queue>
#include <map>
#include <set>
#include <stack>
#include <list>
#include <vector>

using namespace std;

typedef struct Node {
int x;
int y;
};
Node po[22];
int edge[11];
int n;

int dis(int x, int y) {
return x * x + y * y;
}
int solve() {
memset(edge, 0, sizeof(edge));
int ans = 0;
for(int i = 0; i < n; i++) {
for(int j = i+1; j < n; j++) {
for(int p = j+1; p < n; p++) {
for(int q = p+1; q < n; q++) {
edge[0] = dis(po[i].x-po[j].x, po[i].y-po[j].y);
edge[1] = dis(po[i].x-po[p].x, po[i].y-po[p].y);
edge[2] = dis(po[i].x-po[q].x, po[i].y-po[q].y);
edge[3] = dis(po[j].x-po[p].x, po[j].y-po[p].y);
edge[4] = dis(po[j].x-po[q].x, po[j].y-po[q].y);
edge[5] = dis(po[p].x-po[q].x, po[p].y-po[q].y);
sort(edge, edge+6);
if(edge[0] == edge[1] && edge[1] == edge[2] && edge[2] == edge[3] && edge[4] == edge[5]) {
ans++;
}
}
}
}
}
return ans;
}
int main() {
// freopen("in", "r", stdin);
while(~scanf("%d", &n)) {
for(int i = 0; i < n; i++) {
scanf("%d %d", &po[i].x, &po[i].y);
}
printf("%d\n", solve());
}
}