program problema2;
var i,j,s,uc,p:longint;
    n:longint;
begin
write('n=');readln(n);
s:=0;
for i:=1 to n do begin
    p:=1;
    for j:=1 to i do p:=(p mod 10)*i;
    s:=s+p;
end;
uc:=s mod 10;
write('ultima cifra a sumei este',' ',uc);
readln
end.