#include <bits/stdc++.h>
using namespace std;
bool solve() {
  char s[500];
  if (scanf("%s", s) == EOF) return false;
  int in = 0, out = 0;
  for (int i = 0; s[i]; ++i) {
    if (s[i] == '+') {
      if (out) {
        out--;
        in++;
      } else {
        in++;
      }
    } else {
      if (in) {
        in--;
        out++;
      } else {
        out++;
      }
    }
  }
  printf("%d\n", in + out);
  return true;
}
int main() {
  solve();
  return 0;
}
