CF1009A.Game Shopping

Maxim wants to buy some games at the local game shop. There are $n$ games in the shop, the $i$-th game costs $c_i$.

Maxim has a wallet which can be represented as an array of integers. His wallet contains $m$ bills, the $j$-th bill has value $a_j$.

Games in the shop are ordered from left to right, Maxim tries to buy every game in that order.

When Maxim stands at the position $i$ in the shop, he takes the first bill from his wallet (if his wallet is empty then he proceeds to the next position immediately) and tries to buy the $i$-th game using this bill. After Maxim tried to buy the $n$-th game, he leaves the shop.

Maxim buys the $i$-th game if and only if the value of the first bill (which he takes) from his wallet is greater or equal to the cost of the $i$-th game. If he successfully buys the $i$-th game, the first bill from his wallet disappears and the next bill becomes first. Otherwise Maxim leaves the first bill in his wallet (this bill still remains the first one) and proceeds to the next game.

For example, for array $c = [2, 4, 5, 2, 4]$ and array $a = [5, 3, 4, 6]$ the following process takes place: Maxim buys the first game using the first bill (its value is $5$), the bill disappears, after that the second bill (with value $3$) becomes the first one in Maxim's wallet, then Maxim doesn't buy the second game because $c_2 \gt a_2$, the same with the third game, then he buys the fourth game using the bill of value $a_2$ (the third bill becomes the first one in Maxim's wallet) and buys the fifth game using the bill of value $a_3$.

Your task is to get the number of games Maxim will buy.

马克西姆想在当地的游戏商店购买一些游戏。商店里共有 $n$ 款游戏，其中第 $i$ 款游戏的价格为 $c_i$。

马克西姆的钱包可表示为一个整数数组。他的钱包里有 $m$ 张纸币，其中第 $j$ 张纸币的面值为 $a_j$。

商店里的游戏从左到右依次排列，马克西姆按此顺序尝试购买每一款游戏。

当马克西姆站在商店中第 $i$ 个位置时，他从钱包中取出第一张纸币（若钱包为空，则立即前往下一个位置），并尝试用这张纸币购买第 $i$ 款游戏。在马克西姆尝试购买完第 $n$ 款游戏后，他离开商店。

马克西姆成功购买第 $i$ 款游戏，当且仅当他从钱包中取出的第一张纸币的面值大于或等于第 $i$ 款游戏的价格。若他成功购买了第 $i$ 款游戏，则该纸币从钱包中消失，下一张纸币成为钱包中的第一张；否则，该纸币保留在钱包中（仍为第一张），马克西姆继续前往下一款游戏。

例如，对于价格数组 $c = [2, 4, 5, 2, 4]$ 和纸币数组 $a = [5, 3, 4, 6]$，整个过程如下：马克西姆用第一张纸币（面值为 $5$）购买了第一款游戏，该纸币消失；随后第二张纸币（面值为 $3$）成为钱包中的第一张；接着由于 $c_2 > a_2$，他未能购买第二款游戏；同理，他也未能购买第三款游戏；之后，他用面值为 $a_2$ 的纸币（此时第三张纸币已成为钱包中的第一张）购买了第四款游戏，并用面值为 $a_3$ 的纸币购买了第五款游戏。

你的任务是计算马克西姆最终将购买多少款游戏。

The first line of the input contains two integers $n$ and $m$ ($1 \le n, m \le 1000$) — the number of games and the number of bills in Maxim's wallet.

The second line of the input contains $n$ integers $c_1, c_2, \dots, c_n$ ($1 \le c_i \le 1000$), where $c_i$ is the cost of the $i$-th game.

The third line of the input contains $m$ integers $a_1, a_2, \dots, a_m$ ($1 \le a_j \le 1000$), where $a_j$ is the value of the $j$-th bill from the Maxim's wallet.

输入的第一行包含两个整数 $n$ 和 $m$（$1 \le n, m \le 1000$）——分别表示游戏的数量以及 Maxim 钱包中纸币的数量。

输入的第二行包含 $n$ 个整数 $c_1, c_2, \dots, c_n$（$1 \le c_i \le 1000$），其中 $c_i$ 表示第 $i$ 个游戏的价格。

输入的第三行包含 $m$ 个整数 $a_1, a_2, \dots, a_m$（$1 \le a_j \le 1000$），其中 $a_j$ 表示 Maxim 钱包中第 $j$ 张纸币的面值。

Print a single integer — the number of games Maxim will buy.

输出一个整数——Maxim 将购买的游戏数量。

The first example is described in the problem statement.

In the second example Maxim cannot buy any game because the value of the first bill in his wallet is smaller than the cost of any game in the shop.

In the third example the values of the bills in Maxim's wallet are large enough to buy any game he encounter until he runs out of bills in his wallet.

第一个示例已在题目描述中给出。

在第二个示例中，Maxim 无法购买任何游戏，因为其钱包中第一张纸币的面值小于商店中任意一款游戏的价格。

在第三个示例中，Maxim 钱包中纸币的面值足够大，以至于他可以购买所遇到的任意一款游戏，直至钱包中的纸币用尽。