program fibonachi;

{$APPTYPE CONSOLE}
uses
  SysUtils,Windows;
type long=array[0..100000] of integer;

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

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






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

f1[0]:=1;f1[1]:=1;
f2[0]:=1;f2[1]:=1;


for i:=3 to n+1 do begin
//f3:=s3(f1,f2);
f3:=s(f1,f2);
//for j:=f3[0] downto j do write(f3[j]);writeln;  readln;
//for j:=0 to f2[0] do f1[j]:=f2[j];
//for j:=0 to f3[0] do f2[j]:=f3[j];
f1:=f2;
f2:=f3;
end;

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