Cod sursa(job #2568522)
| Utilizator |  Arteni Cristi Arteni_Cristi |
Data | 4 martie 2020 00:26:43 |
|---|---|---|---|
| Problema | Aria | Scor | 0 |
| Compilator | fpc | Status | done |
| Runda | Arhiva educationala | Marime | 0.32 kb |
var n,i:longint;
s,a,b,a1,b1,x,y:real;
begin
assign(input,'aria.in'); reset(input);
assign(output,'aria.out'); rewrite(output);
readln(n);
read(a,b); a1:=a; b1:=b;
for i:=2 to n do
begin
readln(x,y);
s:=s+a*y-b*x;
a:=x;
b:=y
end;
s:=s+a1*y-x*b1;
writeln(s:5:5);
close(input);
close(output)
end.