program nunta; 
type numar=array[0..500] of longint; 
var f, g:text; 
    i, n, t, k, j:longint;    
    z, vg, a, b, c:numar; 
procedure suma(x,y:numar; var z:numar);
begin    
z:=vg;     
t:=0;     
for j:=1 to y[0] do      
begin     
k:=t+x[j]+y[j];        
z[j]:=k mod 10;       
t:=k div 10;      
end;    
z[0]:=y[0];    
if t>0 then     
begin
z[0]:=z[0]+1;        
z[z[0]]:=t;      
end;
end;   
begin  
assign(f,'nunta.in'); reset(f);   
assign(g,'nunta.out'); rewrite(g);   
read(f,n);    
a[0]:=1;     
a[1]:=1;    
b[0]:=1;    
b[1]:=2;    
i:=3;    
while i<=n do     
begin       
suma(a,b,c);
a:=b;         
b:=c;
i:=i+1;      
end;     
if n=1 then      
c:=a;     
if n=2 then      
c:=b;     
for i:=c[0] downto 1 do   
write(g,c[i]); 
writeln(g); 
close(f); 
close(g); 
end.