A superhero fights with a monster. The battle consists of rounds, each of which lasts exactly $n$ minutes. After a round ends, the next round starts immediately. This is repeated over and over again.

Each round has the same scenario. It is described by a sequence of $n$ numbers: $d_1, d_2, \dots, d_n$ ($-10^6 \le d_i \le 10^6$). The $i$-th element means that monster's hp (hit points) changes by the value $d_i$ during the $i$-th minute of each round. Formally, if before the $i$-th minute of a round the monster's hp is $h$, then after the $i$-th minute it changes to $h := h + d_i$.

The monster's initial hp is $H$. It means that before the battle the monster has $H$ hit points. Print the first minute after which the monster dies. The monster dies if its hp is less than or equal to $0$. Print -1 if the battle continues infinitely.

Input

The first line contains two integers $H$ and $n$ ($1 \le H \le 10^{12}$, $1 \le n \le 2\cdot10^5$). The second line contains the sequence of integers $d_1, d_2, \dots, d_n$ ($-10^6 \le d_i \le 10^6$), where $d_i$ is the value to change monster's hp in the $i$-th minute of a round.

Output

Print -1 if the superhero can't kill the monster and the battle will last infinitely. Otherwise, print the positive integer $k$ such that $k$ is the first minute after which the monster is dead.

见题面 Input 部分

见题面 Output 部分