Cafeteria Serving

There are N serving counters numbered 1 to N. Counter i serves food i. M students line up to receive food.

Each student can receive certain foods, and their happiness increases by the value of the food received. The rules are as follows.

• The food numbers that student j can receive are fixed as $p_{j,1}, p_{j,2}, \cdots, p_{j,l_j}$. Each student can receive the same food at most once.
• If student j receives food $p_{j,k}$, their happiness increases by $v_{j,k}$.
• Food received by student j cannot be received by student j+1. ($1 \leq j \leq M-1$)

Initially, every student has happiness 0. Serve the food so that the total happiness of all students is maximized.

The first line contains two integers N and M, separated by a space. ($1 \leq N, M \leq 10^5$)

The next M lines describe the foods each student can eat. On line j, the first integer is $l_j$, the number of foods student j can eat. It is followed by $2l_j$ integers $p_{j,1}, v_{j,1}, p_{j,2}, v_{j,2}, \cdots, p_{j,l_j}, v_{j,l_j}$, separated by spaces. The values $p_{j,k}$ are given in increasing order. ($1 \leq j \leq M$; $1 \leq l_j \leq N$; $1 \leq p_{j,1} < p_{j,2} < \cdots < p_{j,l_j} \leq N$; $1 \leq v_{j,k} \leq 10^9$)

The sum of all $l_j$ does not exceed $10^5$.

Print the maximum possible total happiness of all students.