Cod sursa(job #1653794)

Utilizator medicinedoctoralexandru medicinedoctor Data 16 martie 2016 16:23:20
Problema Aria Scor 0
Compilator fpc Status done
Runda Arhiva educationala Marime 0.25 kb
Raporteaza aceasta sursa 
var a:array [1..2,1..1000] of integer;
i,n:integer; s:real;

begin
  read(n);
  for i:=1 to n do
    read(a[1,i],a[2,i]);
  for i:=1 to n-1 do
    s:=s+(a[1,i]*a[2,i+1]-a[1,i+1]*a[2,i])/2;
  s:=s+(a[1,n]*a[2,1]-a[1,1]*a[2,n])/2;
  write(s);
end.