bzoj1934

var
  ans,u,v,x,tot,kk,i,j,k,l,n,m,ee,s,t:longint;
  d,last,next,long,other,e,head,num:array[0..200000]of longint;

function min(aa,bb:longint):longint;
  begin
  if aa>bb then exit(bb)
  else exit(aa);
  end;

procedure add(u,v,c:longint);
  begin
  inc(kk);
  other[kk]:=kk+1;
  e[kk]:=v;
  next[kk]:=head[u];
  head[u]:=kk;
  long[kk]:=c;
  inc(kk);
  e[kk]:=u;
  next[kk]:=head[v];
  head[v]:=kk;
  long[kk]:=0;
  other[kk]:=kk-1;
  end;

function dfs(x,flow:longint):longint;
  var j,p:longint;
  begin
  if x=t then exit(flow);
  dfs:=0; j:=last[x];
  while j<>0 do
    begin
    if (long[j]>0)and(d[x]=d[e[j]]+1) then
      begin
      last[x]:=j;
      p:=dfs(e[j],min(flow-dfs,long[j]));
      dec(long[j],p); inc(long[other[j]],p);
      dfs:=dfs+p;
      if dfs=flow then exit;
      end;
    j:=next[j];
    end;
  if d[s]>tot then exit;
  dec(num[d[x]]);
  if num[d[x]]=0 then d[s]:=tot;
  inc(d[x]);
  last[x]:=head[x];
  inc(num[d[x]]);
  end;

begin
  readln(n,m);
  s:=0;t:=n+1;
  for i:=1 to n do
    begin
    read(x);
    if x=1 then
      add(s,i,1)
    else
      add(i,t,1);
    end;
  for i:=1 to m do
    begin
    readln(u,v);
    add(u,v,1);
    add(v,u,1);
    end;
  tot:=t+1;
  num[0]:=tot;
  for i:=s to t do
    last[i]:=head[i];
  while d[s]<=tot do
    ans:=ans+dfs(s,maxlongint);
  writeln(ans);
  end.