#coding: UTF-8

import sys
import re
import itertools
from math import log
from collections import deque

### defs ###
def rotate(n):
	return [n[-1]] + n[0:-1]

### main ###
N,M = map(int,sys.stdin.readline().split())
A = list(map(int,sys.stdin.readline().split()))
num = list(range(1,N+1))
for a in A:
	num = rotate(num[0:a]) + num[a:]
print(num[0])