CONTHO Pascal

var n,i:longint;
f:array[0..1000000] of int64;
procedure giai;
begin
    f[0]:=0;
    f[1]:=1;
    for i:=2 to  n do
        f[i]:=f[i-1]+f[i-2];
    write(f[n]);
end;

begin
    assign(input,'contho.inp');reset(input);
    assign(output,'contho.out');rewrite(output);
    read(n);
    giai;
    close(input);
    close(output);
end.