text: #include <cstdio>
  #include <iostream>
  #include <string>
  
  int main(){
  
      std::string inputString("1");
      getline(std::cin, inputString);
  
      bool middleState(0);
      long counter(0);
  
      for(int k = inputString.size() - 1; k >= 0; k--){
          if(!middleState && inputString[k] == '0'){++counter;}
          else if(middleState && inputString[k] == '0'){counter += 2;}
          else if(inputString[k] == '1' && k > 0){++counter; middleState = 1;}
          else if(inputString[k] == '1' && middleState == 1){counter += 2;}
      }
  
      printf("%ld\n", counter);
  
      return 0;
  }
  