program energii;
var e,c:array[0..1001] of longint;
    w,g,i,j,m,s:longint;
    f,g2:text;

begin
assign(f,'energii.in');reset(f);
assign(g2,'energii.out');rewrite(g2);
read(f,g,w);
e[0]:=0;c[0]:=0;
for i:=1 to g do
  begin
    read(f,e[i],c[i]);
    c[i]:=c[i-1]+c[i];
    e[i]:=e[i-1]+e[i];
  end;
m:=10011002;
i:=g;
while i>0 do
  begin
    j:=1;
    s:=e[i]-e[i-j];
    while (s<w) and (i-j>0) do inc(j);
    if (c[i]-c[i-j]<m) and (s>=w) then m:=c[i]-c[i-j];
    dec(i);
  end;
writeln(g2,m);
close(f);
close(g2);
end.