#include <bits/stdc++.h> using namespace std; int n, a[30005], s[30005]; int ans; signed main() { scanf("%d", &n); for (int i=1; i<=n; i++) { scanf("%d", &a[i]); if (a[i] == 1) s[i] = s[i-1] + a[i]; } for (int i=1; i<=n; i++) { if (s[i] > i-s[i]) { if (a[i] == 0) ans++; a[i] = 1; } else { if (a[i] == 1) ans++; a[i] = 0; } } printf("%d", ans); return 0; }