一道pascal题目　　又是一年秋季时,陶陶家的苹果树结了n个果子.陶陶又跑去摘苹果,这次她有一个a公分的椅子.当他手够

var
n,s,a,b,i,j,s1:longint;
x,y:array[1..100]of longint;
begin
readln(n,s);
readln(a,b);
for i:=1 to n do
begin
readln(x[i],y[i]);
if x[i]>(a+b) then x[i]:=0;
end;
for i:=1 to (n-1) do
for j:=i to n do
if y[i]>y[j] then begin
z:=y[i];y[i]:=y[j];y[j]:=z;
end;
for i:=1 to n do
if (s1+y[i]