#include <bits/stdc++.h>
int r, c, p;
int main() {
  while ((c = getchar_unlocked()) != '\n') {
    if (c == p) {
      p = 1;
    } else {
      r += 1;
      p = c == 1 ? 0 : c;
    }
  }
  printf("%d\n", r);
}
