am doar 60 de p , primele 4 WA , spuneti-mi va rog care ii eroare

program p1;
var a,b:array[0..100002] of longint;
b3,b2:array[0..1 shl 17 ] of char;
f,g:text;
i,n,j,k,m,x,y,a1,b1:longint;
aria,nr:int64;
function cmmdc(a1,b1:longint):longint;
begin
if (a1=0) or ( b1=0) then cmmdc:=b1
else cmmdc:=cmmdc(b1,a1 mod b1);
end;
begin
assign(f,'copaci.in');settextbuf(f,b3);reset(F);
assign(g,'copaci.out');settextbuf(g,b2);rewrite(G);
readln(f,n);
for i:=1 to n do
readln(f,a
,b);
a[n+1]:=a[1];
b[n+1]:=b[1];
for i:=1 to n do begin
aria:=aria + (a*b[i+1]-b*a[i+1]);
nr:=nr+cmmdc(abs(a-a[i+1]),abs(b-b[i+1]));
end;
aria:=abs(aria div 2);
write(g,aria-(nr div 2) +1 );
close(F);
close(G);
end.