var a : string;
function HEX_DEC(x:string):longint;
const digits:array [0..15] of char =
('0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F');
var res,ves:longint; i,j:byte;
begin
res:=0; ves:=1;
for i:=length(x) downto 1 do begin
j:=0; a[i]:=UpCase(a[i]);
while (digits[j]<>x[i]) do inc(j);
res:=res+ves*j;
ves:=ves*16;
end;
HEX_DEC:=res;
end;
begin { основная программа }
readln( a );
writeln( HEX_DEC(a) );
end.