#include <iostream>
#include <vector>
using namespace std;

constexpr int inf = 987'654'321;

int f(string s) {
  s = '0' + s;
  int n = static_cast<int>(s.size());
  // dp[繰り上がったか] := 最小回数
  vector<int> dp(2, inf);
  dp[0] = 0;
  for(int i=n-1; i>=0; --i) { // 下から
    vector<int> ndp(2, inf);
    for(int carry=0; carry<2; ++carry) {
      if(dp[carry] == inf) { continue; }
      for(int d : {-1, 0, 1}) {
        int val    = (carry + d + s[i]-'0') % 2,
            ncarry = (carry + d + s[i]-'0') / 2;
        if(val != 0) { continue; }
        ndp[ncarry] = min(ndp[ncarry], dp[carry] + abs(d));
      }
    }
    dp = ndp;
  }
  int res = dp[0];
  return res;
}

int main(void) {
  string s; cin >> s;
  int res = f(s);
  printf("%d\n", res);
  return 0;
}