uses math;

const maxn=;

      INF=;

var n,m,i,x,y,sum,ans,delta:longint;

    map:array[..maxn,..maxn] of longint;

    flag:array[..maxn] of boolean;

    T:double;

    ok:boolean;

function ran:double;

begin

    exit(random()/);

end;

procedure add(x,y:longint);

begin

    inc(map[x,]); map[x,map[x,]]:=y;

end;

begin

    randomize;

    readln(n,m);

    for i:= to m do

    begin

        readln(x,y);

        add(x,y);

        add(y,x);

    end;

    fillchar(flag,sizeof(flag),true);

    T:=0.1;

    sum:=n; ans:=INF;

    while T>0.000001 do

    begin

        T:=T*0.999;

        repeat

            x:=random(n)+;

        until flag[x];

        delta:=-;

        for i:= to map[x,] do

        begin

            if map[x,i]=x then inc(delta);

            if not flag[map[x,i]] then inc(delta);

        end;

        ok:=false;

        if delta< then ok:=true

        else

            if ran<exp(-delta/T) then ok:=true;

        if ok then

        begin

            sum:=sum+delta;

            if sum<ans then ans:=sum;

            flag[x]:=false;

            for i:= to map[x,] do

                flag[map[x,i]]:=true;

        end;

    end;

    writeln(ans);

end.