var a,b:array[1..10000]of integer;
i,j,m,t,n,sum:integer;
begin
read(n,m);
for i:=1 to n do read(a[i]); //读入两个数组

for i:=1 to m do read(b[i]);
for i:=1 to n-1 do //冒泡排序a数组
for j:=1 to n-i do
if a[j]<a[j+1] then
begin
t:=a[j]; a[j]:=a[j+1]; a[j+1]:=t;
end;
for i:=1 to n-1 do //冒泡排序b数组
for j:=1 to n-i do
if b[j]<b[j+1] then
begin
t:=b[j]; b[j]:=b[j+1]; b[j+1]:=t;
end;
sum:=0; //计数器清零
for i:=1 to n do
for j:=1 to m do
if (a[i]>b[j]) and (b[j]<>0) then //如果陶陶的高度小于不等于零苹果的高度则
begin
b[j]:=0; //清零
inc(sum);
break; //退出循环
end;
write(sum);
end.