bzoj2285

完全是为了拼凑才出出来的吧
先分数规划求出到基地入口的最小安全系数
然后再最小点权覆盖集，只不过这里是带一定精度实数的流，其实是一样的

const inf=100000000;
      eps=0.001;
type way=record
       po,next,ti,sa:longint;
     end;
     node=record
       po,next:longint;
       flow:double;
     end;

var w:array[0..100010] of way;
    e:array[0..100010] of node;
    d:array[0..800] of double;
    numh,h,pp,p,cur,pre:array[0..800] of longint;
    q:array[0..2000010] of longint;
    v:array[0..800] of boolean;
    i,t,n,m,m1,len,x,y,z,b:longint;
    ans:double;

function min(a,b:double):double;
  begin
    if a>b then exit(b) else exit(a);
  end;

procedure add(x,y,a,b:longint);
  begin
    inc(len);
    w[len].po:=y;
    w[len].ti:=a;
    w[len].sa:=b;
    w[len].next:=pp[x];
    pp[x]:=len;
  end;

procedure ins(x,y:longint;f:double);
  begin
    inc(len);
    e[len].po:=y;
    e[len].flow:=f;
    e[len].next:=p[x];
    p[x]:=len;
  end;

function check(t:longint;m:double):boolean;
  var x,y,f,r,i:longint;
  begin
    for i:=1 to n do
      d[i]:=inf;
    d[n]:=0;
    fillchar(v,sizeof(v),false);
    f:=1;
    r:=1;
    q[1]:=n;
    while f<=r do
    begin
      x:=q[f];
      v[x]:=false;
      i:=pp[x];
      while i<>0 do
      begin
        y:=w[i].po;
        if d[y]>d[x]+w[i].ti-m*w[i].sa then
        begin
          d[y]:=d[x]+w[i].ti-m*w[i].sa;
          if (y=t) and (d[y]<=0) then exit(true);
          if not v[y] then
          begin
            v[y]:=true;
            inc(r);
            q[r]:=y;
          end;
        end;
        i:=w[i].next;
      end;
      inc(f);
    end;
    if d[t]<=0 then exit(true) else exit(false);
  end;

function calc(x:longint):double;
  var l,r,m:double;
  begin
    l:=0;
    r:=10;
    if not check(x,10) then exit(inf);
    while r-l>eps do
    begin
      m:=(l+r)/2;
      if check(x,m) then r:=m else l:=m;
    end;
    exit(r);
  end;

procedure sap;
  var u,i,j,tmp,q:longint;
      neck:double;
  begin
    u:=0;
    for i:=0 to t do
      cur[i]:=p[i];
    numh[0]:=t+1;
    neck:=inf;
    while h[0]<t+1 do
    begin
      d[u]:=neck;
      i:=cur[u];
      while i<>-1 do
      begin
        j:=e[i].po;
        if (e[i].flow>0) and (h[u]=h[j]+1) then
        begin
          pre[j]:=u;
          cur[u]:=i;
          neck:=min(neck,e[i].flow);
          u:=j;
          if u=t then
          begin
            ans:=ans+neck;
            if ans>inf then exit;
            while u<>0 do
            begin
              u:=pre[u];
              j:=cur[u];
              e[j].flow:=e[j].flow-neck;
              e[j xor 1].flow:=e[j xor 1].flow+neck;
            end;
            neck:=inf;
          end;
          break;
        end;
        i:=e[i].next;
      end;
      if i=-1 then
      begin
        dec(numh[h[u]]);
        if numh[h[u]]=0 then exit;
        tmp:=t;
        q:=-1;
        i:=p[u];
        while i<>-1 do
        begin
          j:=e[i].po;
          if e[i].flow>0 then
            if tmp>h[j] then
            begin
              tmp:=h[j];
              q:=i;
            end;
          i:=e[i].next;
        end;
        h[u]:=tmp+1;
        inc(numh[h[u]]);
        cur[u]:=q;
        if u<>0 then
        begin
          u:=pre[u];
          neck:=d[u];
        end;
      end;
    end;
  end;

begin
  readln(n,m);
  for i:=1 to m do
  begin
    readln(x,y,z,b);
    add(x,y,z,b);
  end;
  len:=-1;
  fillchar(p,sizeof(p),255);
  readln(m1,t);
  inc(t);
  for i:=1 to t-1 do
    if i mod 2=0 then
    begin
      ins(i,t,calc(i));
      ins(t,i,0);
    end
    else begin
      ins(0,i,calc(i));
      ins(i,0,0);
    end;

  for i:=1 to m1 do
  begin
    readln(x,y);
    ins(x,y,inf);
    ins(y,x,0);
  end;
  sap;
  if ans>inf then writeln(-1)
  else writeln(ans:0:1);
end.