// yukicoder: No.123 カードシャッフル
// 2019.5.13 bal4u

#include <stdio.h>

#if 1
#define gc() getchar_unlocked()
#else
#define gc() getchar()
#endif
int in()
{
	int n = 0, c = gc();
	do n = 10*n + (c & 0xf), c = gc(); while (c >= '0');
	return n;
}

typedef struct { int id, prev, next; } T;
T t[52];
int top, end;
int res;

void card(int n) {
	int i;
	for (i = 0; i < n; i++) t[i].id = i+1, t[i].prev = i-1, t[i].next = i+1;
	top = 0, end = n-1, res = 1;
}

void shuffle(int a) {
	int k, p, n;
	if (a == 1) return;
	k = top; while (--a) k = t[k].next;
	res = t[k].id, p = t[k].prev, n = t[k].next;
	if (k != end) t[p].next = n, t[n].prev = p;
	t[k].next = top, t[top].prev = k;
	top = k, end = p;
}

int main()
{
	int N, M;

	N = in();
	if (N == 1) { puts("1"); return 0; }
	card(N);
	M = in(); while (M--) shuffle(in());
	printf("%d\n", res);
	return 0;
}