program douazeci;
var i,n,x,er:integer;
    p,nr:longint;
    s:string;
    c:char;

begin
write('introduceti nr de caractere ');
readln(n);
s:='';
for i:=1 to n do begin
write('caracterul este ');
repeat
readln(c);
until ((c>='0') and (c<='9')) or ((upcase(c)>='A') and (upcase(c)<='F'));
s:=s+c;
end;
p:=1;
nr:=0;
for i:=length(s) downto 1 do begin
if upcase(s[i])='A' then
nr:=nr+p*10
else if upcase(s[i])='B' then
nr:=nr+p*11
else if upcase(s[i])='C' then
nr:=nr+p*12
else if upcase(s[i])='D' then
nr:=nr+p*13
else if upcase(s[i])='E' then
nr:=nr+p*14
else if upcase(s[i])='F' then
nr:=nr+p*15
else
begin
val(s[i],x,er);
nr:=nr+x*p;
end;
p:=p*16;
end;
writeln(nr);
readln;
end.