Program AddNums(output);
type
int64 = longint;
function fibo(n:integer):int64;
var
a1,a2,pom:int64;
i:integer;
begin
a1:=0;a2:=1;i:=1;
while(i<=n)do
begin
pom:= a2;
a2:= a1 + a2;
a1:= pom;
inc(i);
end;
fibo:=a1;
end;
var
n:integer;
begin
readln(n);
writeln(fibo(n));
end.
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