#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef double db; 
typedef string str; 

typedef pair<int,int> pi;
typedef pair<ll,ll> pl; 
typedef pair<db,db> pd; 

typedef vector<int> vi; 
typedef vector<ll> vl; 
typedef vector<db> vd; 
typedef vector<str> vs; 
typedef vector<pi> vpi;
typedef vector<pl> vpl; 
typedef vector<pd> vpd; 

#define mp make_pair
#define f first
#define s second
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend() 
#define rsz resize
#define ins insert 
#define ft front() 
#define bk back()
#define pf push_front 
#define pb push_back
#define eb emplace_back 
#define lb lower_bound 
#define ub upper_bound 

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

const int MOD = 1e9+7; // 998244353;
const int MX = 1e6+5; 
const ll INF = 1e18; 
const ld PI = acos((ld)-1);
const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; 
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 

template<class T> bool ckmin(T& a, const T& b) { 
	return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { 
	return a < b ? a = b, 1 : 0; } 
int pct(int x) { return __builtin_popcount(x); } 
int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) 
int cdiv(int a, int b) { return a/b+!(a<0||a%b == 0); } // division of a by b rounded up, assumes b > 0 
int fstTrue(function<bool(int)> f, int lo, int hi) {
	hi ++; assert(lo <= hi); // assuming f is increasing
	while (lo < hi) { // find first index such that f is true 
		int mid = (lo+hi)/2; 
		f(mid) ? hi = mid : lo = mid+1; 
	} 
	return lo;
}

// INPUT
template<class A> void re(complex<A>& c);
template<class A, class B> void re(pair<A,B>& p);
template<class A> void re(vector<A>& v);
template<class A, size_t SZ> void re(array<A,SZ>& a);

template<class T> void re(T& x) { cin >> x; }
void re(db& d) { str t; re(t); d = stod(t); }
void re(ld& d) { str t; re(t); d = stold(t); }
template<class H, class... T> void re(H& h, T&... t) { re(h); re(t...); }

template<class A> void re(complex<A>& c) { A a,b; re(a,b); c = {a,b}; }
template<class A, class B> void re(pair<A,B>& p) { re(p.f,p.s); }
template<class A> void re(vector<A>& x) { trav(a,x) re(a); }
template<class A, size_t SZ> void re(array<A,SZ>& x) { trav(a,x) re(a); }

// TO_STRING
#define ts to_string
str ts(char c) { return str(1,c); }
str ts(bool b) { return b ? "true" : "false"; }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
template<class A> str ts(complex<A> c) { 
	stringstream ss; ss << c; return ss.str(); }
str ts(vector<bool> v) { 
	str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]);
	res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) {
	str res = ""; F0R(i,SZ) res += char('0'+b[i]);
	return res; }
template<class A, class B> str ts(pair<A,B> p);
template<class T> str ts(T v) { // containers with begin(), end()
	bool fst = 1; str res = "{";
	for (const auto& x: v) {
		if (!fst) res += ", ";
		fst = 0; res += ts(x);
	}
	res += "}"; return res;
}
template<class A, class B> str ts(pair<A,B> p) {
	return "("+ts(p.f)+", "+ts(p.s)+")"; }

// OUTPUT
template<class A> void pr(A x) { cout << ts(x); }
template<class H, class... T> void pr(const H& h, const T&... t) { 
	pr(h); pr(t...); }
void ps() { pr("\n"); } // print w/ spaces
template<class H, class... T> void ps(const H& h, const T&... t) { 
	pr(h); if (sizeof...(t)) pr(" "); ps(t...); }

// DEBUG
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {
	cerr << ts(h); if (sizeof...(t)) cerr << ", ";
	DBG(t...); }
#ifdef LOCAL // compile with -DLOCAL
#define dbg(...) cerr << "LINE(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif

// FILE I/O
void setIn(string s) { freopen(s.c_str(),"r",stdin); }
void setOut(string s) { freopen(s.c_str(),"w",stdout); }
void unsyncIO() { ios_base::sync_with_stdio(0); cin.tie(0); }
void setIO(string s = "") {
	unsyncIO();
	// cin.exceptions(cin.failbit); 
	// throws exception when do smth illegal
	// ex. try to read letter into int
	if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
}

int stor[1<<20];

/**
 * Description: 1D range update and query, $SZ=2^p$.
 * Source: USACO Counting Haybales
 * Verification: SPOJ Horrible
 */

template<class T, int SZ> struct LazySeg { 
	T mn[2*SZ], mx[2*SZ], lazy[2*SZ]; 
	LazySeg() { F0R(i,2*SZ) mn[i] = mx[i] = lazy[i] = 0; }
	void push(int ind, int L, int R) { /// modify values for current node
		if (L != R) F0R(i,2) lazy[2*ind+i] += lazy[ind]; /// prop to children
		mn[ind] += lazy[ind]; mx[ind] += lazy[ind];
		lazy[ind] = 0; 
	} // recalc values for current node
	void pull(int ind) { 
		mn[ind] = min(mn[2*ind],mn[2*ind+1]); 
		mx[ind] = max(mx[2*ind],mx[2*ind+1]); 
	}
	void build(int ind = 1, int L = 0, int R = SZ-1) {
		lazy[ind] = 0;
		if (L == R) {
			mn[ind] = mx[ind] = stor[L];
			return;
		}
		int M = (L+R)/2;
		build(2*ind,L,M); build(2*ind+1,M+1,R);
		pull(ind);
	}
	void upd(int lo,int hi,T inc,int ind=1,int L=0, int R=SZ-1) {
		push(ind,L,R); if (hi < L || R < lo) return;
		if (lo <= L && R <= hi) { 
			lazy[ind] = inc; push(ind,L,R); return; }
		int M = (L+R)/2; upd(lo,hi,inc,2*ind,L,M); 
		upd(lo,hi,inc,2*ind+1,M+1,R); pull(ind);
	}
	T qmax(int lo, int hi, int ind=1, int L=0, int R = SZ-1) {
		push(ind,L,R); if (lo > R || L > hi) return -MOD;
		if (lo <= L && R <= hi) return mx[ind];
		int M = (L+R)/2; 
		return max(qmax(lo,hi,2*ind,L,M),qmax(lo,hi,2*ind+1,M+1,R));
	}
	T qmin(int lo, int hi, int ind=1, int L=0, int R = SZ-1) {
		push(ind,L,R); if (lo > R || L > hi) return MOD;
		if (lo <= L && R <= hi) return mn[ind];
		int M = (L+R)/2; 
		return min(qmin(lo,hi,2*ind,L,M),qmin(lo,hi,2*ind+1,M+1,R));
	}
	int getMin(T x, int ind=1, int L=0, int R = SZ-1) { // max <= x
		push(ind,L,R); 
		if (mx[ind] <= x) return L; // OK
		if (L == R) return MOD;
		int M = (L+R)/2;
		int t = getMin(x,2*ind+1,M+1,R); if (t > M+1) return t;
		int u = getMin(x,2*ind,L,M); return u == MOD ? t : u;
	}
};

LazySeg<int,1<<20> L;

str S;

/*int getMin(int x) {
	int lo = 0, hi = sz(S)+1;
	while (lo < hi) {
		int mid = (lo+hi)/2;
		if (L.qmax(mid,sz(S)) > x) lo = mid+1;
		else hi = mid;
	}
	return lo;
}*/

int ans = MOD;

void tri(int mx) {
	L.build(1);
	set<int> change;
	F0R(i,sz(S)) if (S[i] == '?') change.insert(i);
	for (;;mx += 2) {
		while (sz(change)) {
			int ind = L.getMin(mx-2)-1; 
			auto it = change.lb(ind); if (it == end(change)) break;
			int i = *it; change.erase(it);
			L.upd(i+1,(1<<20)-1,2);
		}
		ckmin(ans,mx-L.qmin(0,(1<<20)-1));
		if (!sz(change)) return;
	}
}

int main() {
	setIO(); re(S);
	{
		int bal = 0;
		F0R(i,sz(S)) {
			if (S[i] == '0' || S[i] == '?') bal --;
			else bal ++;
			stor[i+1] = bal;
		}
		FOR(i,sz(S)+1,1<<20) stor[i] = stor[sz(S)];
	}
	int bal = 0, mx = 0;
	trav(c,S) {
		if (c == '0' || c == '?') bal --;
		else bal ++;
		ckmax(mx,bal);
	}
	tri(mx); tri(mx+1);
	ps(ans);
	// you should actually read the stuff at the bottom
}

/* stuff you should look for
	* int overflow, array bounds
	* special cases (n=1?)
	* do smth instead of nothing and stay organized
	* WRITE STUFF DOWN
*/



Measured memory_bytes: 79776