Problem p03482 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <array>
#include <cmath>
#include <complex>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <valarray>
#include <vector>
// cin.sync_with_stdio(false);
// streambuf
using namespace std;
typedef long long ll;
typedef double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
using vi = vector<int>;
using vll = vector<ll>;
using vpii = vector<pii>;
using vpll = vector<pll>;
using ti3 = tuple<int, int, int>;
using vti3 = vector<ti3>;
template <class T, int s> using va = vector<array<T, s>>;
template <class T, class T2> using umap = unordered_map<T, T2>;
template <class T> using uset = unordered_set<T>;
template <class T, class S> void cmin(T &a, const S &b) {
  if (a > b)
    a = b;
}
template <class T, class S> void cmax(T &a, const S &b) {
  if (a < b)
    a = b;
}
#define ALL(a) a.begin(), a.end()
#define rep(i, a) for (int i = 0; i < a; i++)
#define rep1(i, a) for (int i = 1; i <= a; i++)
#define rrep(i, a) for (int i = (a)-1; i >= 0; i--)
#define rrep1(i, a) for (int i = a; i; i--)
#define repi(i, a, b) for (int i = a; i < b; i++)
const ll mod = 1000000007;
template <class T> using heap = priority_queue<T, vector<T>, greater<T>>;
template <class T> using pque = priority_queue<T, vector<T>, function<T(T, T)>>;
template <class T> inline void hash_combine(size_t &seed, const T &v) {
  hash<T> hasher;
  seed ^= hasher(v) + 0x9e3779b97f4a7c15 + (seed << 6) + (seed >> 2);
}
namespace std {
template <typename S, typename T> struct hash<pair<S, T>> {
  inline size_t operator()(const pair<S, T> &v) const {
    size_t seed = 0;
    hash_combine(seed, v.first);
    hash_combine(seed, v.second);
    return seed;
  }
};
// Recursive template code derived from Matthieu M.
template <class Tuple, size_t Index = std::tuple_size<Tuple>::value - 1>
struct HashValueImpl {
  static void apply(size_t &seed, Tuple const &tuple) {
    HashValueImpl<Tuple, Index - 1>::apply(seed, tuple);
    hash_combine(seed, std::get<Index>(tuple));
  }
};
template <class Tuple> struct HashValueImpl<Tuple, 0> {
  static void apply(size_t &seed, Tuple const &tuple) {
    hash_combine(seed, std::get<0>(tuple));
  }
};
template <typename... TT> struct hash<std::tuple<TT...>> {
  size_t operator()(std::tuple<TT...> const &tt) const {
    size_t seed = 0;
    HashValueImpl<std::tuple<TT...>>::apply(seed, tt);
    return seed;
  }
};
} // namespace std
template <class T> int id(vector<T> &a, T b) {
  return lower_bound(ALL(a), b) - a.begin();
}
ll pow(ll base, ll i, ll mod) {
  ll a = 1;
  while (i) {
    if (i & 1) {
      a *= base;
      a %= mod;
    }
    base *= base;
    base %= mod;
    i /= 2;
  }
  return a;
}
ll gcd(ll a, ll b) {
  while (b) {
    ll c = a % b;
    a = b;
    b = c;
  }
  return a;
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
#ifdef _MSC_VER
#include <intrin.h>
#endif
int popcnt(unsigned long long a) {
#ifndef _MSC_VER
  return __builtin_popcountll(a);
#else
  return _mm_popcnt_u32(a >> 32) + _mm_popcnt_u32(a);
  a = (a & 0x5555555555555555) + (a >> 1 & 0x5555555555555555);
  a = (a & 0x3333333333333333) + (a >> 2 & 0x3333333333333333);
  a = (a & 0x0f0f0f0f0f0f0f0f) + (a >> 4 & 0x0f0f0f0f0f0f0f0f);
  a = (a & 0x00ff00ff00ff00ff) + (a >> 8 & 0x00ff00ff00ff00ff);
  a = (a & 0x0000ffff0000ffff) + (a >> 16 & 0x0000ffff0000ffff);
  return (a & 0xffffffff) + (a >> 32);
#endif
}
int BitScanF(unsigned long a) {
#ifndef _MSC_VER
  return __builtin_ctzll(a);
#else
  _BitScanForward(&a, a);
  return a;
#endif
}
int BitScanR(unsigned long a) {
#ifndef _MSC_VER
  return 63 - __builtin_clzll(a);
#else
  _BitScanReverse(&a, a);
  return a;
#endif
}
template <class T> class matrix {
public:
  vector<valarray<T>> obj;
  pair<int, int> s;

public:
  matrix(pair<int, int> size, T e = 0) : matrix(size.first, size.second, e) {}
  matrix(int n, int m = -1, T e = 0)
      : obj(n, valarray<T>(e, m == -1 ? n : m)), s(n, m == -1 ? n : m) {}
  static matrix e(int n) {
    matrix a = (n);
    for (int i = 0; i < n; i++)
      a[i][i] = 1;
    return a;
  }
  matrix &operator+=(const matrix &p) {
    if (s != p.s)
      throw runtime_error("matrix error");
    for (int i = 0; i < s.first; i++)
      for (int j = 0; j < s.second; j++)
        obj[i][j] += p.obj[i][j];
    return *this;
  }
  matrix operator+(const matrix &p) {
    matrix res(*this);
    return res += p;
  }
  matrix &operator-=(const matrix &p) {
    if (s != p.s)
      throw runtime_error("matrix error");
    for (int i = 0; i < s.first; i++)
      for (int j = 0; j < s.second; j++)
        obj[i][j] -= p.obj[i][j];
    return *this;
  }
  matrix operator-(const matrix &p) {
    matrix res(*this);
    return res -= p;
  }
  matrix &operator*=(T p) {
    for (auto &a : obj)
      for (auto &b : a)
        b *= p;
    return *this;
  }
  matrix operator*(T p) {
    matrix res(*this);
    return res *= p;
  }
  matrix operator*(const matrix &p) {
    if (s.second != p.s.first)
      throw runtime_error("matrix error");
    matrix ret(s.first, p.s.second);
    for (int i = 0; i < s.first; i++)
      for (int j = 0; j < s.second; j++)
        ret[i] += obj[i][j] * p.obj[j];
    return ret;
  }
  matrix &operator*=(const matrix &p) { return *this = *this * p; }
  bool operator==(const matrix &p) {
    if (s != p.s)
      return 0;
    rep(i, s.first) rep(j, s.second) if (obj[i][j] != p.obj[i][j]) return 0;
    return 1;
  }
  pair<int, int> size() const { return s; }
  matrix &mod(T m) {
    for (auto &a : obj)
      for (auto &b : a)
        b %= m;
    return *this;
  }
  valarray<T> &operator[](int t) { return obj[t]; }
  void gauss() {
    if (size().first + 1 != size().second)
      return;
    rep(i, size().first) {
      int p = i;
      repi(j, i, size().first) if (abs(obj[j][i]) > abs(obj[p][i])) p = j;
      swap(obj[i], obj[p]);
      if (abs(obj[i][i]) < 1e-8)
        return; // contniue;
      repi(j, i + 1, size().second) obj[i][j] /= obj[i][i];
      rep(j, size().first) {
        if (i != j) {
          repi(k, i + 1, size().second) obj[j][k] -= obj[j][i] * obj[i][k];
        }
      }
    }
  }
};
template <class T>
inline matrix<T> pow(matrix<T> &base, unsigned long long exp) {
  auto base_(base);
  if (base_.size().first != base_.size().second)
    throw runtime_error("matrix error");
  matrix<T> res = matrix<T>::e(base_.size().first);
  for (;;) {
    if (exp & 1)
      res *= base_;
    if (res.obj[0].size() > 100) {
      int a = 0;
    }
    if (!(exp /= 2))
      break;
    base_ *= base_;
  }
  return res;
}
template <class T>
inline matrix<T> modpow(matrix<T> &base, unsigned long long exp, ll m) {
  auto base_(base);
  if (base.size().first != base_.size().second)
    throw runtime_error("matrix error");
  matrix<T> res = matrix<T>::e(base_.size().first);
  for (;;) {
    if (exp & 1)
      (res *= base_).mod(m);
    if (res.obj[0].size() > 100) {
      int a = 0;
    }
    if (!(exp /= 2))
      break;
    (base_ *= base_).mod(m);
  }
  return res;
}
class unionfind {
  vector<int> par, rank,
      size_; // 速度ではなくメモリ効率を考えるならrankのかわりにsizeを使う
public:
  unionfind(int n) : par(n), rank(n), size_(n, 1) { iota(ALL(par), 0); }
  int find(int x) {
    if (par[x] == x)
      return x;
    return par[x] = find(par[x]);
  }
  void unite(int x, int y) {
    x = find(x), y = find(y);
    if (x == y)
      return;
    if (rank[x] < rank[y])
      swap(x, y);
    par[y] = x;
    size_[x] += size_[y];
    if (rank[x] == rank[y])
      rank[x]++;
  }
  bool same(int x, int y) { return find(x) == find(y); }
  int size(int x) { return size_[find(x)]; }
};
// end of lib
// template<class S=void,int ptr_num, class T = char>class trie {
//	umap<T, trie<S, ptr_num, T> next;
// public:
//	S key;
//	trie<S, ptr_num, T>* ptr[ptr_num] = {};
//	trie(S &&data) :key(data) {}
//	trie(const S &data) :key(data) {}
//	void add(T x,S data) {
//		if (!next.find(x))next.insert(x, data);
//	}
//	trie& operator[](T x) {
//		return next[x];
//	}
//	bool find(T x) {
//		retun next.find(x);
//	}
// };
// template<class T=char>class AhoCorasick {
//	trie<pair<bool,int>, 2, T> tree;
//	AhoCorasick(vector<string> p) {
//		int num = 0;
//		vector<decltype(&tree)> que(p.size(),&tree);
//		for (int i = 0;; i++) {
//			bool end = 1;
//			int i = 0;
//			for (auto a : p) {
//				if (i >= a.size())break;
//				end = ;0
//				que[i] = (*que[i])[a[i]];
//				i++;
//			}
//			if (end)break;
//		}
//	}　
// };
template <class T, class Func = function<T(T, T)>> class segtree {
  vector<T> obj;
  int offset;
  Func updater;
  T e;
  int bufsize(int num) {
    int i = 1;
    for (; num > i; i <<= 1)
      ;
    offset = i - 1;
    return (i << 1) - 1;
  }
  T query(int a, int b, int k, int l, int r) {
    if (r <= a || b <= l)
      return e;
    if (a <= l && r <= b)
      return obj[k];
    else
      return updater(query(a, b, k * 2 + 1, l, (l + r) / 2),
                     query(a, b, k * 2 + 2, (l + r) / 2, r));
  }

public:
  T query(int a, int b) { //[a,b)
    return query(a, b, 0, 0, offset + 1);
  }
  void updateall(int l = 0, int r = -1) {
    if (r < 0)
      r = offset + 1;
    l += offset, r += offset;
    if (l == 0)
      return;
    do {
      l = l - 1 >> 1, r = r - 1 >> 1;
      for (int i = l; i < r; i++)
        obj[i] = updater(obj[i * 2 + 1], obj[i * 2 + 2]);
    } while (l);
  }
  void update(int k, T &a) {
    k += offset;
    obj[k] = a;
    while (k) {
      k = k - 1 >> 1;
      obj[k] = updater(obj[k * 2 + 1], obj[k * 2 + 2]);
    }
  }
  segtree(int n, T e, const Func &updater = Func())
      : obj(bufsize(n), e), e(e), updater(updater) {}
  segtree(vector<T> &vec, T e, const Func &updater = Func())
      : obj(bufsize(vec.size()), e), e(e), updater(updater) {
    copy(vec.begin(), vec.end(), obj.begin() + offset);
    updateall();
  }
  T &operator[](int n) { return obj[n + offset]; }
};
template <class T = int>
class BIT { // 多次元BITはループをネストすればいいらしい。
  vector<T> bit;

public:
  BIT(int n) : bit(n + 1, 0) {}
  void add(int i, T x) {
    while (i <= bit.size()) {
      bit[i] += x;
      i += i & -i;
    }
  }
  T sum(int i) {
    T s = 0;
    while (i) {
      s += bit[i];
      i &= i - 1;
    }
    return s;
  }
};
template <class T> class rangeadd {
  BIT<T> b0, b1;
  int n;
  rangeadd(int n) : b0(n), b1(n), n(n) {}
  void add(int l, int r, T x) { //[l,r)
    b0.add(l, -x(l - 1));
    b1.add(l, x);
    b0.add(r, x * r);
    b1.add(r, -x);
  }
  T sum(int i) { return b0.sum(i) + b1.sum(i) * i; }
};
int main() {
  ll x, y;
  cin >> x >> y;
  cout << BitScanR(y / x) + 1 << endl;
}
// template<class T, class map = std::unordered_map<T,unique_ptr<node>>>
/*class AhoCorasick {
        struct node {
                map<char,unique_ptr<node>> next;
                node* fail = nullptr, *match_list = nullptr;
                std::vector<int> match;
        }root;
        int pattern;
        //template<class string>
        AhoCorasick(std::vector<string> &vs) :pattern(vs.size()) {
                root.fail = &root;
                for (int i = 0; i < vs.size(); i++) {
                        node* now = &root;
                        for (auto c : vs[i]) {
                                if
(!now->next[c])now->next[c]=make_unique<node>(); now = now->next[c].get();
                        }
                        now->match.push_back(i);
                }
                std::queue<node*> que;
                que.push(&root);
                while (!que.empty()) {
                        auto now = que.front();
                        que.pop();
                        for (auto &next : now->next) {
                                if (!next.second)continue;
                                if
(now->fail->next.count(next.first))next.second->fail =
now->fail->next[next.first].get(); else next.second->fail = now->fail->fail;
                                //next.second->match.insert(next.second->match.end(),
next.second->fail->match.begin(), next.second->fail->match.end()); if
(next.second->fail->match.empty())next.second->match_list =
next.second->fail->match_list; else next.second->match_list = next.second->fail;
                                que.push(next.second.get());
                        }
                }
        }
        auto match_n(string str) {
                vector<int> num(pattern);

        }
        auto match_list(string str) {
                vector<pair<int, int>> list;
                auto now = &root;
                for (int i = 0; i < str.size(); i++) {
                        if (now->next.count(str[i]))now =
now->next[str[i]].get(); else now = now->fail; auto match = now->match_list; do
{ match
                        }
                }
        }
};*/

Fixed submission:
#include <algorithm>
#include <array>
#include <cmath>
#include <complex>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <valarray>
#include <vector>
// cin.sync_with_stdio(false);
// streambuf
using namespace std;
typedef long long ll;
typedef double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
using vi = vector<int>;
using vll = vector<ll>;
using vpii = vector<pii>;
using vpll = vector<pll>;
using ti3 = tuple<int, int, int>;
using vti3 = vector<ti3>;
template <class T, int s> using va = vector<array<T, s>>;
template <class T, class T2> using umap = unordered_map<T, T2>;
template <class T> using uset = unordered_set<T>;
template <class T, class S> void cmin(T &a, const S &b) {
  if (a > b)
    a = b;
}
template <class T, class S> void cmax(T &a, const S &b) {
  if (a < b)
    a = b;
}
#define ALL(a) a.begin(), a.end()
#define rep(i, a) for (int i = 0; i < a; i++)
#define rep1(i, a) for (int i = 1; i <= a; i++)
#define rrep(i, a) for (int i = (a)-1; i >= 0; i--)
#define rrep1(i, a) for (int i = a; i; i--)
#define repi(i, a, b) for (int i = a; i < b; i++)
const ll mod = 1000000007;
template <class T> using heap = priority_queue<T, vector<T>, greater<T>>;
template <class T> using pque = priority_queue<T, vector<T>, function<T(T, T)>>;
template <class T> inline void hash_combine(size_t &seed, const T &v) {
  hash<T> hasher;
  seed ^= hasher(v) + 0x9e3779b97f4a7c15 + (seed << 6) + (seed >> 2);
}
namespace std {
template <typename S, typename T> struct hash<pair<S, T>> {
  inline size_t operator()(const pair<S, T> &v) const {
    size_t seed = 0;
    hash_combine(seed, v.first);
    hash_combine(seed, v.second);
    return seed;
  }
};
// Recursive template code derived from Matthieu M.
template <class Tuple, size_t Index = std::tuple_size<Tuple>::value - 1>
struct HashValueImpl {
  static void apply(size_t &seed, Tuple const &tuple) {
    HashValueImpl<Tuple, Index - 1>::apply(seed, tuple);
    hash_combine(seed, std::get<Index>(tuple));
  }
};
template <class Tuple> struct HashValueImpl<Tuple, 0> {
  static void apply(size_t &seed, Tuple const &tuple) {
    hash_combine(seed, std::get<0>(tuple));
  }
};
template <typename... TT> struct hash<std::tuple<TT...>> {
  size_t operator()(std::tuple<TT...> const &tt) const {
    size_t seed = 0;
    HashValueImpl<std::tuple<TT...>>::apply(seed, tt);
    return seed;
  }
};
} // namespace std
template <class T> int id(vector<T> &a, T b) {
  return lower_bound(ALL(a), b) - a.begin();
}
ll pow(ll base, ll i, ll mod) {
  ll a = 1;
  while (i) {
    if (i & 1) {
      a *= base;
      a %= mod;
    }
    base *= base;
    base %= mod;
    i /= 2;
  }
  return a;
}
ll gcd(ll a, ll b) {
  while (b) {
    ll c = a % b;
    a = b;
    b = c;
  }
  return a;
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
#ifdef _MSC_VER
#include <intrin.h>
#endif
int popcnt(unsigned long long a) {
#ifndef _MSC_VER
  return __builtin_popcountll(a);
#else
  return _mm_popcnt_u32(a >> 32) + _mm_popcnt_u32(a);
  a = (a & 0x5555555555555555) + (a >> 1 & 0x5555555555555555);
  a = (a & 0x3333333333333333) + (a >> 2 & 0x3333333333333333);
  a = (a & 0x0f0f0f0f0f0f0f0f) + (a >> 4 & 0x0f0f0f0f0f0f0f0f);
  a = (a & 0x00ff00ff00ff00ff) + (a >> 8 & 0x00ff00ff00ff00ff);
  a = (a & 0x0000ffff0000ffff) + (a >> 16 & 0x0000ffff0000ffff);
  return (a & 0xffffffff) + (a >> 32);
#endif
}
int BitScanF(unsigned long a) {
#ifndef _MSC_VER
  return __builtin_ctzll(a);
#else
  _BitScanForward(&a, a);
  return a;
#endif
}
int BitScanR(unsigned long a) {
#ifndef _MSC_VER
  return 63 - __builtin_clzll(a);
#else
  _BitScanReverse(&a, a);
  return a;
#endif
}
template <class T> class matrix {
public:
  vector<valarray<T>> obj;
  pair<int, int> s;

public:
  matrix(pair<int, int> size, T e = 0) : matrix(size.first, size.second, e) {}
  matrix(int n, int m = -1, T e = 0)
      : obj(n, valarray<T>(e, m == -1 ? n : m)), s(n, m == -1 ? n : m) {}
  static matrix e(int n) {
    matrix a = (n);
    for (int i = 0; i < n; i++)
      a[i][i] = 1;
    return a;
  }
  matrix &operator+=(const matrix &p) {
    if (s != p.s)
      throw runtime_error("matrix error");
    for (int i = 0; i < s.first; i++)
      for (int j = 0; j < s.second; j++)
        obj[i][j] += p.obj[i][j];
    return *this;
  }
  matrix operator+(const matrix &p) {
    matrix res(*this);
    return res += p;
  }
  matrix &operator-=(const matrix &p) {
    if (s != p.s)
      throw runtime_error("matrix error");
    for (int i = 0; i < s.first; i++)
      for (int j = 0; j < s.second; j++)
        obj[i][j] -= p.obj[i][j];
    return *this;
  }
  matrix operator-(const matrix &p) {
    matrix res(*this);
    return res -= p;
  }
  matrix &operator*=(T p) {
    for (auto &a : obj)
      for (auto &b : a)
        b *= p;
    return *this;
  }
  matrix operator*(T p) {
    matrix res(*this);
    return res *= p;
  }
  matrix operator*(const matrix &p) {
    if (s.second != p.s.first)
      throw runtime_error("matrix error");
    matrix ret(s.first, p.s.second);
    for (int i = 0; i < s.first; i++)
      for (int j = 0; j < s.second; j++)
        ret[i] += obj[i][j] * p.obj[j];
    return ret;
  }
  matrix &operator*=(const matrix &p) { return *this = *this * p; }
  bool operator==(const matrix &p) {
    if (s != p.s)
      return 0;
    rep(i, s.first) rep(j, s.second) if (obj[i][j] != p.obj[i][j]) return 0;
    return 1;
  }
  pair<int, int> size() const { return s; }
  matrix &mod(T m) {
    for (auto &a : obj)
      for (auto &b : a)
        b %= m;
    return *this;
  }
  valarray<T> &operator[](int t) { return obj[t]; }
  void gauss() {
    if (size().first + 1 != size().second)
      return;
    rep(i, size().first) {
      int p = i;
      repi(j, i, size().first) if (abs(obj[j][i]) > abs(obj[p][i])) p = j;
      swap(obj[i], obj[p]);
      if (abs(obj[i][i]) < 1e-8)
        return; // contniue;
      repi(j, i + 1, size().second) obj[i][j] /= obj[i][i];
      rep(j, size().first) {
        if (i != j) {
          repi(k, i + 1, size().second) obj[j][k] -= obj[j][i] * obj[i][k];
        }
      }
    }
  }
};
template <class T>
inline matrix<T> pow(matrix<T> &base, unsigned long long exp) {
  auto base_(base);
  if (base_.size().first != base_.size().second)
    throw runtime_error("matrix error");
  matrix<T> res = matrix<T>::e(base_.size().first);
  for (;;) {
    if (exp & 1)
      res *= base_;
    if (res.obj[0].size() > 100) {
      int a = 0;
    }
    if (!(exp /= 2))
      break;
    base_ *= base_;
  }
  return res;
}
template <class T>
inline matrix<T> modpow(matrix<T> &base, unsigned long long exp, ll m) {
  auto base_(base);
  if (base.size().first != base_.size().second)
    throw runtime_error("matrix error");
  matrix<T> res = matrix<T>::e(base_.size().first);
  for (;;) {
    if (exp & 1)
      (res *= base_).mod(m);
    if (res.obj[0].size() > 100) {
      int a = 0;
    }
    if (!(exp /= 2))
      break;
    (base_ *= base_).mod(m);
  }
  return res;
}
class unionfind {
  vector<int> par, rank,
      size_; // 速度ではなくメモリ効率を考えるならrankのかわりにsizeを使う
public:
  unionfind(int n) : par(n), rank(n), size_(n, 1) { iota(ALL(par), 0); }
  int find(int x) {
    if (par[x] == x)
      return x;
    return par[x] = find(par[x]);
  }
  void unite(int x, int y) {
    x = find(x), y = find(y);
    if (x == y)
      return;
    if (rank[x] < rank[y])
      swap(x, y);
    par[y] = x;
    size_[x] += size_[y];
    if (rank[x] == rank[y])
      rank[x]++;
  }
  bool same(int x, int y) { return find(x) == find(y); }
  int size(int x) { return size_[find(x)]; }
};
// end of lib
// template<class S=void,int ptr_num, class T = char>class trie {
//	umap<T, trie<S, ptr_num, T> next;
// public:
//	S key;
//	trie<S, ptr_num, T>* ptr[ptr_num] = {};
//	trie(S &&data) :key(data) {}
//	trie(const S &data) :key(data) {}
//	void add(T x,S data) {
//		if (!next.find(x))next.insert(x, data);
//	}
//	trie& operator[](T x) {
//		return next[x];
//	}
//	bool find(T x) {
//		retun next.find(x);
//	}
// };
// template<class T=char>class AhoCorasick {
//	trie<pair<bool,int>, 2, T> tree;
//	AhoCorasick(vector<string> p) {
//		int num = 0;
//		vector<decltype(&tree)> que(p.size(),&tree);
//		for (int i = 0;; i++) {
//			bool end = 1;
//			int i = 0;
//			for (auto a : p) {
//				if (i >= a.size())break;
//				end = ;0
//				que[i] = (*que[i])[a[i]];
//				i++;
//			}
//			if (end)break;
//		}
//	}　
// };
template <class T, class Func = function<T(T, T)>> class segtree {
  vector<T> obj;
  int offset;
  Func updater;
  T e;
  int bufsize(int num) {
    int i = 1;
    for (; num > i; i <<= 1)
      ;
    offset = i - 1;
    return (i << 1) - 1;
  }
  T query(int a, int b, int k, int l, int r) {
    if (r <= a || b <= l)
      return e;
    if (a <= l && r <= b)
      return obj[k];
    else
      return updater(query(a, b, k * 2 + 1, l, (l + r) / 2),
                     query(a, b, k * 2 + 2, (l + r) / 2, r));
  }

public:
  T query(int a, int b) { //[a,b)
    return query(a, b, 0, 0, offset + 1);
  }
  void updateall(int l = 0, int r = -1) {
    if (r < 0)
      r = offset + 1;
    l += offset, r += offset;
    if (l == 0)
      return;
    do {
      l = l - 1 >> 1, r = r - 1 >> 1;
      for (int i = l; i < r; i++)
        obj[i] = updater(obj[i * 2 + 1], obj[i * 2 + 2]);
    } while (l);
  }
  void update(int k, T &a) {
    k += offset;
    obj[k] = a;
    while (k) {
      k = k - 1 >> 1;
      obj[k] = updater(obj[k * 2 + 1], obj[k * 2 + 2]);
    }
  }
  segtree(int n, T e, const Func &updater = Func())
      : obj(bufsize(n), e), e(e), updater(updater) {}
  segtree(vector<T> &vec, T e, const Func &updater = Func())
      : obj(bufsize(vec.size()), e), e(e), updater(updater) {
    copy(vec.begin(), vec.end(), obj.begin() + offset);
    updateall();
  }
  T &operator[](int n) { return obj[n + offset]; }
};
template <class T = int>
class BIT { // 多次元BITはループをネストすればいいらしい。
  vector<T> bit;

public:
  BIT(int n) : bit(n + 1, 0) {}
  void add(int i, T x) {
    while (i <= bit.size()) {
      bit[i] += x;
      i += i & -i;
    }
  }
  T sum(int i) {
    T s = 0;
    while (i) {
      s += bit[i];
      i &= i - 1;
    }
    return s;
  }
};
template <class T> class rangeadd {
  BIT<T> b0, b1;
  int n;
  rangeadd(int n) : b0(n), b1(n), n(n) {}
  void add(int l, int r, T x) { //[l,r)
    b0.add(l, -x(l - 1));
    b1.add(l, x);
    b0.add(r, x * r);
    b1.add(r, -x);
  }
  T sum(int i) { return b0.sum(i) + b1.sum(i) * i; }
};
int main() {
  string s;
  cin >> s;
  int start = -1;
  int ans = s.size();
  rep(i, s.size()) {
    if (s[i] == '0')
      start = i;
    else if (i == s.size() - 1 && start == -1)
      ans = s.size();
    else if (i == s.size() - 1)
      ans = min(ans, max(i - start, start + 1));
    else if (start == -1 && s[i + 1] == '0')
      ans = max((int)s.size() - i - 1, i + 1);
    else if (s[i + 1] == '0')
      ans = min(ans, max(min((int)s.size() - start - 1, i + 1),
                         max((int)s.size() - i - 1, start + 1)));
  }
  cout << ans << endl;
}
// template<class T, class map = std::unordered_map<T,unique_ptr<node>>>
/*class AhoCorasick {
        struct node {
                map<char,unique_ptr<node>> next;
                node* fail = nullptr, *match_list = nullptr;
                std::vector<int> match;
        }root;
        int pattern;
        //template<class string>
        AhoCorasick(std::vector<string> &vs) :pattern(vs.size()) {
                root.fail = &root;
                for (int i = 0; i < vs.size(); i++) {
                        node* now = &root;
                        for (auto c : vs[i]) {
                                if
(!now->next[c])now->next[c]=make_unique<node>(); now = now->next[c].get();
                        }
                        now->match.push_back(i);
                }
                std::queue<node*> que;
                que.push(&root);
                while (!que.empty()) {
                        auto now = que.front();
                        que.pop();
                        for (auto &next : now->next) {
                                if (!next.second)continue;
                                if
(now->fail->next.count(next.first))next.second->fail =
now->fail->next[next.first].get(); else next.second->fail = now->fail->fail;
                                //next.second->match.insert(next.second->match.end(),
next.second->fail->match.begin(), next.second->fail->match.end()); if
(next.second->fail->match.empty())next.second->match_list =
next.second->fail->match_list; else next.second->match_list = next.second->fail;
                                que.push(next.second.get());
                        }
                }
        }
        auto match_n(string str) {
                vector<int> num(pattern);

        }
        auto match_list(string str) {
                vector<pair<int, int>> list;
                auto now = &root;
                for (int i = 0; i < str.size(); i++) {
                        if (now->next.count(str[i]))now =
now->next[str[i]].get(); else now = now->fail; auto match = now->match_list; do
{ match
                        }
                }
        }
};*/