#include <stdio.h>

int main()
{
	int i, N, A[200001];
	scanf("%d", &N);
	for (i = 1; i <= N; i++) scanf("%d", &(A[i]));
	
	int tmp;
	long long ans = 0;
	for (i = N - 1, tmp = 0; i >= 1; i--) {
		if (A[i+1] != A[i]) tmp++;
		else tmp = 1;
		if (A[i] == 1) ans += tmp;
	}
	printf("%lld\n", ans);
	fflush(stdout);
	return 0;
}