var f,g:text;
    n,i,g1,s,p,j,o:longint;
    a,b:array[1..5000]of longint;
    c:array[1..5000]of longint;

begin
assign(f,'rucsac.in');
assign(g,'rucsac.out');
reset(f);
rewrite(g);
read(f,n);
read(f,g1);
for I:=1 to n do
begin
read(f,a[i]);
read(f,b[i]);
end;
for i:=1 to n do
c[i]:=trunc(b[i]/a[i]);

for i:=1 to n do
for j:=i+1 to n do
if c[i]<c[j] then
begin
o:=c

[i];
c[i]:=c[j];
c[j]:=o;
o:=a[i];
a[i]:=a[j];
a[j]:=o;
o:=b[i];
b[i]:=b[j];
b[j]:=o;
end;
j:=1;
s:=0;
p:=a[1];
while p<g1 do
begin
s:=s+b[j];
j:=j+1;
p:=p+a[j];
end;
write(g,s);
close(f);
close(g);
end.