#include <bits/stdc++.h>
// #include <atcoder/all>
using namespace std;
// using namespace atcoder;
using ll = long long;
using pll = pair<ll, ll>;
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(),(x).end()
#define sz(x) ((long long)(x).size())
#define rep_(i, a_, b_, a, b, ...) for (long long i = (a), lim##i = (b); i < lim##i; i++)
#define rep(i, ...) rep_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__)
#define V(type, name, ...) vector<type> name(__VA_ARGS__)
#define VV(type, name, h, ...) vector<vector<type>> name(h, vector<type>(__VA_ARGS__))
#define VVV(type, name, h, w, ...) vector<vector<vector<type>>> name(h, vector<vector<type>>(w, vector<type>(__VA_ARGS__)))
#ifndef dump
#define dump(...)
#define db(x)
#define vdb(v)
#define vvdb(v)
#define mdb(m)
#define sdb(s)
#endif
template<class T> inline bool chmax(T& a, T b) {if (a < b) {a = b; return 1;} return 0; }
template<class T> inline bool chmin(T& a, T b) {if (a > b) {a = b; return 1;} return 0; }
const ll LINF = 1LL << 60;
const int INF = INT_MAX;
const long double EPS = 1e-10;
const long double PI = acos(-1);
int di[] = {1, 0, -1, 0};
int dj[] = {0, 1, 0, -1};
// using mint = modint1000000007; const ll MOD = 1000000007;
// using mint = modint998244353; const ll MOD = 998244353;



int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    string S; cin >> S;
    cout << (sz(S) + 2 - 1) / 2 << endl;
    
}