#include <bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;
// const int mod = 998244353;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}

int main() {
  string S;
  cin >> S;

  int high = 0;
  for(int i = 0, sum = 0; i < S.size(); i++) {
    sum += S[i] == '0' ? -1 : 1;
    chmax(high, sum);
  }
  int low = 0;
  for(int i = 0, sum = 0; i < S.size(); i++) {
    sum += S[i] == '1' ? 1 : -1;
    chmax(low, sum);
  }
  ++high;
  int ret = inf;
  auto check = [&](int high_val) {
    vector< int > suff(S.size() + 1);
    for(int i = S.size() - 1; i >= 0; i--) {
      if(S[i] == '1') {
        suff[i] = suff[i + 1] + 1;
      } else {
        suff[i] = suff[i + 1] - 1;
      }
      chmax(suff[i], 0);
    }
    int low_val = 0;
    for(int i = 0, sum = 0; i < S.size(); i++) {
      if(S[i] == '1') {
        sum += 1;
      } else if(S[i] == '0') {
        sum -= 1;
      } else {
        sum += 1;
        if(sum + suff[i + 1] > high_val) {
          sum -= 2;
        }
      }
      chmin(low_val, sum);
    }
    chmin(ret, high_val - low_val);
    return high_val - low_val;
  };
  check(low);
  check(high - 1);
  while(high - low > 1) {
    int mid = (high + low) / 2;
    if(check(mid) - check(mid - 1) > 0) high = mid;
    else low = mid;
  }
  cout << ret << endl;
}


Measured memory_bytes: 8216