program haromszog;
var x,y:array[1..1500] of double;
    n,i,j,k:integer;
    f,g:text;
    d1,d2,d3:longint;

begin
        assign(f,'triang.in');reset(f);
        assign(g,'triang.out');rewrite(g);
        readln(f,n);
        for i:=1 to n do begin
                read(f,x[i]);
                readln(f,y[i]);end;

        for i:=1 to n-2 do
                for j:=i+1 to n-1 do
                        for k:=j+1 to n do begin
                                d1:=(x[j]-x[i])*(x[j]-x[i])+
                                   (y[j]-y[i])*(y[j]-y[i]);
                                d2:=(x[k]-x[i])*(x[k]-x[i])+
                                   (y[k]-y[i])*(y[k]-y[i]);
                                d3:=(x[j]-x[k])*(x[j]-x[k])+
                                   (y[j]-y[k])*(y[j]-y[k]);
                                if (d1=d2) or (d2=d3) or (d3=d1) then inc(db);
                                end;

        write(g,db);
        close(f);close(g);
end.