program p1;
var f,g:text;
    n,st,dr,mij,j,p:longint;

function desc_5(x:longint):longint;
var m,y,s:longint;
begin
     y:=5;s:=0;
     while x div y>0 do
     begin
          s:=s+x div y;
          y:=y*5;
     end;
     desc_5:=s;
end;

begin
     assign(f,'fact.in');reset(f);
     assign(g,'fact.out');rewrite(g);
     read(f,p);
     st:=1;dr:=p*5;
     while st<=dr do
     begin
          mij:=(st+dr) div 2;
          if desc_5(mij)>=p then begin dr:=mij-1;j:=mij;end
             else st:=mij+1;
     end;
     if desc_5(j)=p then write(g,j)
        else writeln(g,'0');
     close(f);
     close(g);
end.