#include <stdio.h>

const int Mod = 1000000007;

int main()
{
	int i, N, P[101];
	scanf("%d", &N);
	for (i = 1; i <= N; i++) scanf("%d", &(P[i]));
	
	int j, cur, prev, dp[2][101][2] = {};
	for (i = 1, cur = 1, prev = 0, dp[0][0][0] = 1; i <= N; i++, cur ^= 1, prev ^= 1) {
		for (j = 0, dp[cur][0][0] = 0, dp[cur][0][1] = 0; j < i; j++) {
			dp[cur][j][0] += dp[prev][j][0];
			if (dp[cur][j][0] >= Mod) dp[cur][j][0] -= Mod;
			dp[cur][j][1] += dp[prev][j][1];
			if (dp[cur][j][1] >= Mod) dp[cur][j][1] -= Mod;
			
			if (P[i] > 50) {
				dp[cur][j+1][0] = dp[prev][j][1];
				dp[cur][j+1][1] = dp[prev][j][0];
			} else if (P[i] < 50) {
				dp[cur][j+1][0] = dp[prev][j][0];
				dp[cur][j+1][1] = dp[prev][j][1];
			} else {
				dp[cur][j+1][0] = 0;
				dp[cur][j+1][1] = 0;
			}
		}
	}
	
	long long ans = 0;
	for (j = 1; j <= N; j++) ans += dp[prev][j][1];
	printf("%lld\n", ans % Mod);
	fflush(stdout);
	return 0;
}