program p1002;

var

st,st1:array[0..101] of longint;

a,value:array[0..10100] of longint;

l,s,t,m,i,sum,j:longint;

begin

readln(l);

readln(s,t,m);

for i:=1 to m do read(st[i]);

st[0]:=0;st[m+1]:=l;

sum:=0;

for i:=1 to m+1 do

if st[i]-st>100 then

begin

st1[i]:=st1+100;sum:=sum+st[i]-st-100;

end

else

st1[i]:=st1+st[i]-st;

l:=l-sum;

fillchar(a,sizeof(a),0);

for i:=1 to m do

a[st1[i]]:=1;

value[0]:=0;

for i:=1 to l do value[i]:=99999999;

for i:=1 to l do

for j:=s to t do

if i>=j then

if value+a[i]