Description

To be able to surf the Internet, Pero bought a data plan:

• Each month, he gets $x \rm{MB}$ of data.
• Any unused data from a month can be carried over to the next month.

Now we know how many $\rm{MB}$ of data Pero used in each of the first $n$ months of this plan. Please calculate how many $\rm{MB}$ of data he can use in month $n+1$.

Input Format

The first line contains an integer $x$.

The second line contains an integer $n$.

The next $n$ lines each contain an integer $p_i$, which indicates how many $\rm{MB}$ of data Pero used in month $i$.

Output Format

Output one line with one integer, representing how many $\rm{MB}$ of data Pero can use in month $n+1$.

10
3
4
6
2 

28

10
3
10
2
12 

16

15
3
15
10
20 

15

Hint

Sample 1 Explanation

In the first month, Pero can use $10\rm{MB}$ of data. He actually uses $4\rm{MB}$, leaving $6\rm{MB}$.

In the second month, Pero can use $6+10=16(\rm{MB})$ of data. He actually uses $6\rm{MB}$, leaving $10\rm{MB}$.

In the third month, Pero can use $10+10=20(\rm{MB})$ of data. He actually uses $2\rm{MB}$, leaving $18\rm{MB}$.

In the fourth month, Pero can use $18+10=28(\rm{MB)}$ of data.

Constraints

For $100\%$ of the testdata, it is guaranteed that $1\le x\le 100$, $1\le n\le 100$, and $0\le p_i\le 10^4$.

Notes

This problem is translated from COCI2016-2017 CONTEST #1 T1 Tarifa.

Translated by ChatGPT 5