var N,m,m1,m2,i:integer;beginread(N);m1:=1;m2:=0;for i:=2 to N do beginm:=m1+m2;m2:=m1;m1:=m;end;write(m);end.
var N,m,m1,m2,i:integer;
begin
read(N);
m1:=1;
m2:=0;
for i:=2 to N do begin
m:=m1+m2;
m2:=m1;
m1:=m;
end;
write(m);
end.