import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.complex, std.container, std.math, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const S = readToken();
      const L = cast(int)(S.length);
      
      int bsf;
      for (bsf = 0; S[L - 1 - bsf] == '0'; ++bsf) {}
      auto dp = new int[][](L + 1, 2);
      dp[bsf + 1][0] = 1;
      dp[bsf + 1][1] = 1;
      foreach (i; bsf + 1 .. L) {
        if (S[L - 1 - i] == '0') {
          dp[i + 1][0] = min(dp[i][0], 1 + dp[i][1]);
          dp[i + 1][1] = 1 + dp[i][1];
        } else {
          dp[i + 1][0] = 1 + dp[i][0];
          dp[i + 1][1] = min(dp[i][1], 1 + dp[i][0]);
        }
      }
      debug {
        writeln("bsf = ", bsf);
        writeln("dp = ", dp);
      }
      const ans = min(dp[L][0], 1 + dp[L][1]);
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}