// A: Placing Marbles
"use strict";

const DEBUG_MODE = false;
const rawInput = DEBUG_MODE
  ? "000"
  : require("fs")
      .readFileSync("/dev/stdin", "utf8")
      .trim();

const process = inputRaw => {
  console.log((inputRaw.match(/1/g) || []).length);
};

process(rawInput);
