#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define all(a) a.begin(), a.end() #define rep(i, n) for (ll i = 0; i < (n); i++) #define range(i, a, b) for (ll i = (a); i < (b); i++) #define pb push_back #define debug(x) cerr << __LINE__ << ' ' << #x << ':' << (x) << '\n' #pragma GCC optimize("O3") #pragma GCC optimize("unroll-loops") using namespace std; typedef long long ll; typedef unsigned int uint; typedef unsigned long long ull; typedef long double ld; typedef pair P; typedef complex com; template using pri_s = priority_queue, greater>; template using pri_b = priority_queue; constexpr int inf = 1000000010; constexpr ll INF = 1000000000000000010; constexpr int mod1e9 = 1000000007; constexpr int mod998 = 998244353; constexpr ld eps = 1e-12; constexpr ld pi = 3.141592653589793238; constexpr ll ten(int n) { return n ? 10 * ten(n - 1) : 1; }; int dx[] = { 1,0,-1,0,1,1,-1,-1 }; int dy[] = { 0,1,0,-1,1,-1,1,-1 }; ll mul(ll a, ll b) { return (a > INF / b ? INF : a * b); } void fail() { cout << "-1\n"; exit(0); } void no() { cout << "No\n"; exit(0); } template void er(T a) { cout << a << '\n'; exit(0); } template inline bool chmax(T &a, const U &b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(T &a, const U &b) { if (a > b) { a = b; return true; } return false; } template istream &operator >> (istream &s, vector &v) { for (auto &e : v) s >> e; return s; } template ostream &operator << (ostream &s, const vector &v) { for (auto &e : v) s << e << ' '; return s; } template ostream &operator << (ostream &s, const pair &p) { s << p.first << ' ' << p.second; return s; } struct fastio { fastio() { cin.tie(0); cout.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); cerr << fixed << setprecision(20); } }fastio_; template class segtree { int n; vector data; T id = 0; T operation(T a, T b) { return a + b; }; public: segtree(int _n) { n = 1; while (n < _n + 2) n <<= 1; data = vector(2 * n, id); } segtree(vector vec) { int _n = vec.size(); n = 1; while (n < _n + 2) n <<= 1; data = vector(2 * n, id); for (int i = 0; i < _n; i++) data[i + n] = vec[i]; for (int i = n - 1; i >= 1; i--) data[i] = operation(data[i << 1], data[i << 1 | 1]); } void change(int i, T x) { i += n; data[i] = x; while (i > 1) { i >>= 1; data[i] = operation(data[i << 1], data[i << 1 | 1]); } } void add(int i, T x) { change(i, data[i + n] + x); } T get(int a, int b) { T left = id; T right = id; a += n; b += n; while (a < b) { if (a & 1) left = operation(left, data[a++]); if (b & 1) right = operation(data[--b], right); a >>= 1; b >>= 1; } return operation(left, right); } T get_all() { return data[1]; } T operator[](int i) { return data[i + n]; } }; int main() { int n; cin >> n; string s; cin >> s; vector one; rep(i, n) if (s[i] == '1') one.pb(i); int sz = one.size(); if (sz == 0) er(0); rep(i, sz) one.pb(one[i] + n); vector d; d.pb(0); rep(i, 2 * sz - 1) d.pb(one[i + 1] - one[i] - 1); rep(i, 2 * sz - 1) d[i + 1] += d[i]; segtree seg(2 * n); rep(i, sz) seg.change(d[i], 1); ll ans = INF; rep(i, sz) { int ok = n, ng = -1; while (ok - ng > 1) { int mid = (ok + ng) / 2; int r = mid + d[i]; int g = seg.get(r + 1, 2 * n); if (d[sz - 1] - d[i] <= mid && g != 0) g++; if (g <= mid) ok = mid; else ng = mid; } int res = ok * n + d[i + sz - 1] - d[i] - ok; if (i != 0) res -= one[i - 1] + 1; chmax(res, 0); chmin(ans, res); seg.change(d[i], 0); seg.change(d[i + sz], 1); } cout << ans << '\n'; }