#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define SIZE 31

struct long_num {
	int size;
	char digs[1000];
};

void lsum(struct long_num *_1, struct long_num *_2, struct long_num *result, int offset) {
	int i, carry = 0;
	result->size = _1->size + offset > _2->size ? _1->size + offset : _2->size;
	for(i = _1->size; i < result->size + offset; i ++)
		_1->digs[i] = 0;
	for(i = _2->size; i < result->size + offset; i ++)
		_2->digs[i] = 0;
	for(i = 0; i < offset; i ++) {
		result->digs[i] = _2->digs[i];
	}
	for(i = offset; i < result->size; i ++) {
		int val = carry + _1->digs[i] + _2->digs[i + offset];
		result->digs[i + offset] = val % 10;
		carry = val / 10;
	}
	if(carry)
		result->digs[result->size ++] = carry;
}

void lmults(struct long_num *n, int by, struct long_num *result) {
	int i, carry = 0;
	result->size = n->size;
	for(i = 0; i < n->size; i ++) {
		int val = carry + n->digs[i] * by;
		result->digs[i] = val % 10;
		carry = val / 10;
	}
	while(carry) {
		result->digs[result->size ++] = carry % 10;
		carry /= 10;
	}
}

void lmult(struct long_num *_1, struct long_num *_2, struct long_num *result) {
	struct long_num m, tmp;
	int i;
	result->size = 0;
	for(i = 0; i < _1->size; i ++) {
		lmults(_2, _1->digs[i], &m);
		memmove(m.digs + i, m.digs, m.size * sizeof *m.digs);
		m.size += i;
		memset(m.digs, 0, i * sizeof *m.digs);
		lsum(&m, result, &tmp, 0);
		*result = tmp;
	}
}

void lprint(struct long_num *_1) {
	int i;
	for(i = _1->size - 1; i >= 0; i --)
		putchar('0' + _1->digs[i]);
}

struct long_num table[SIZE][SIZE];

struct node {
	unsigned value;
	struct node *l, *r;
	unsigned count;
	struct long_num result;
} data[SIZE], *root;

unsigned ncount;

struct long_num one;

void compute(struct node *n) {
	struct long_num *lresult = &one, *rresult = &one, result;
	unsigned lcount = 0, rcount = 0;
	if(n->l) {
		compute(n->l);
		lresult = &n->l->result;
		lcount = n->l->count;
	}
	if(n->r) {
		compute(n->r);
		rresult = &n->r->result;
		rcount = n->r->count;
	}
	n->count = lcount + rcount + 1;
	lmult(lresult, rresult, &result);
	lmult(&result, &table[lcount][rcount], &n->result);
}

int main(int argc, char *argv[]) {
	unsigned i, j;
	one.size = 1;
	one.digs[0] = 1;
	for(i = 0; i < SIZE; i++) {
		table[0][i].size = 1;
		table[0][i].digs[0] = 1;
	}
	for(i = 1; i < SIZE; i ++) {
		table[i][0].size = 1;
		table[i][0].digs[0] = 1;
		for(j = 1; j < SIZE; j++) {
			lsum(&table[i-1][j], &table[i][j-1], &table[i][j], 0);
		}
	}
	while(scanf("%u", &ncount), ncount) {
		for(i = 0; i < ncount; i ++) {
			unsigned value;
			struct node **pos = &root;
			scanf("%u", &value);
			while(*pos) {
				if((*pos)->value > value)
					pos = &(*pos)->l;
				else
					pos = &(*pos)->r;
			}
			*pos = &data[i];
			(*pos)->value = value;
			(*pos)->l = (*pos)->r = NULL;
		}
		compute(root);
		lprint(&root->result);
		putchar('\n');
	}
	return 0;
}