program convoy(input,output);
var
 n,m,l:int64;
 i,j:longint;
 temp,lest:int64;
 a:array[0..1000,1..2]of int64;
 f:Array[0..1001]of double;

begin
 assign(input,'convoy.in');
 reset(input);
 readln(m,l,n);
 for i:=1 to n do readln(a[i,1],a[i,2]);
 close(input);

 for i:=1 to n do
 begin
  temp:=a[i,1];
  lest:=a[i,2];
  f[i]:=f[i-1]+l/a[i,2];
  for j:=i-1 downto 0 do
  begin
   if temp>m then break;
   if f[i]>f[j]+l/lest
    then f[i]:=f[j]+l/lest;
   temp:=temp+a[j,1];
   if lest>a[j,2] then lest:=a[j,2];
  end;
 end;

 assign(output,'convoy.out');
 rewrite(output);
 writeln((f[n]*60):0:1);
 close(output);
end.