Program BTH;
Uses crt;
Var i:byte;
s,n:qword;
Function mu(b:qword): qword;
Var i:longint;
s:qword;
Begin
s:=1;
For i:=1 to b do
s:=s*b;
mu:=s;
End;
Begin
clrscr;
Write('Nhap n: '); Readln(n);
s:=0;
For i:=1 to n do
s:=s+mu(i);
Write('Tong day so tren la ',s);
readln;
End.