Program vv;
Var f,g:Text;
    i,p,n:Longword;
Begin
 Assign (f,'fact.in');Reset (f);
 Assign (g,'fact,out');Rewrite (g);
 Readln (f,p);
 n:=1;
 If p=0 then n:=1
 Else
 If p=1 then n:=1
 Else
 Begin
  For i:=1 to p do
  n:=n*i;
 End;
 Writeln (g,n);
 Close (f);Close (g);
End.