var
    max,len,n:int64;
    i,j:longint;
    w,v,f:array[0..1000]of extended;
    minv,t:extended;
begin
    assign(input,'convoy.in');
    assign(output,'convoy.out');
    reset(input);rewrite(output);
    read(max,len,n);
    for i:=1 to n do
    read(w[i],v[i]);
    f[0]:=0;
    f[1]:=len/v[1];
    for i:=2 to n do
       begin
            f[i]:=1e24;
            minv:=1e24;
            t:=0;
            for j:=i downto 1 do
               begin
                    t:=t+w[j];
                   if v[j]<minv then minv:=v[j];
                  if t>max then break;
                  if minv<>0 then if f[j-1]+len/minv<f[i] then f[i]:=f[j-1]+len/minv;
             end;
      end;
    writeln(f[n]*60:0:1);
    close(input);
    close(output);
end.