program fibonachi;

{$APPTYPE CONSOLE}
uses
  SysUtils,
  Windows;

type long=record
n:word;
a:array[0..10000] of byte;
end;

var f1,f2,f3:long;
n,i,j:integer;
time:int64;

function s(a,b:long):long;
var c:long;
os,i:integer;
begin
if a.n>b.n then c.n:=a.n else c.n:=b.n;
os:=0;
for i:=1 to c.n do begin
c.a[i]:=(a.a[i]+b.a[i]+os) mod 10;
os:=(a.a[i]+b.a[i]+os) div 10;
end;
if os>0 then begin c.n:=c.n+1;c.a[c.n]:=os;end;
//s:=c;
for i:=1 to c.n do s.a[i]:=c.a[i];
s.n:=c.n;

end;



begin
readln(n);
time:=GetTickCount;
//f1:='1'; f2:='1';

f1.n:=1;f1.a[1]:=1;
f2.n:=1;f2.a[1]:=1;


for i:=3 to n+1 do begin
//f3:=s3(f1,f2);
f3:=s(f1,f2);
for j:=1 to f2.n do f1.a[j]:=f2.a[j];
f1.n:=f2.n;
for j:=1 to f3.n do f2.a[j]:=f3.a[j];
f2.n:=f3.n;
//f1:=f2;f2:=f3;
end;

//writeln(f3);
for i:=f3.n downto 1 do write(f3.a[i]);
writeln;
time:=GetTickCount-time;
writeln((time/1000):0:5);
readln;
end.