#include <bits/stdc++.h> using namespace std; using ll=long long; using vin=vector<int>; using vll=vector<long long>; using vvin=vector<vector<int>>; using vvll=vector<vector<long long>>; using vstr=vector<string>; using vvstr=vector<vector<string>>; using vch=vector<char>; using vvch=vector<vector<char>>; using vbo=vector<bool>; using vvbo=vector<vector<bool>>; using vpii=vector<pair<int,int>>; using pqsin=priority_queue<int,vector<int>,greater<int>>; #define mp make_pair #define rep(i,n) for(int i=0;i<(int)(n);i++) #define rep2(i,s,n) for(int i=(s);i<(int)(n);i++) #define all(v) v.begin(),v.end() #define decp(n) cout<<fixed<<setprecision((int)n) const int inf=1e9+7; const ll INF=1e18; int main(){ string s;cin>>s; int zero=0; rep(i,s.size()-1)if(s[i+1]!='0')zero++; cout<<zero<<endl; }