a:array[0..50]of longint;

begin

read(p,s,n);

for i:=1 to s do

read(a[i]);

i:=1;

while n<a[i] do inc(i);

if i<p then write(i)

else if (i=p)and(n>a[p])then write(i)

else write(-1);

end.