#include <bits/stdc++.h>
using namespace std;
string st;
int len;
int main() {
  cin >> st;
  len = st.size();
  int obrace = INT_MAX - 10, cbrace = INT_MIN + 10, fcolon, lcolon;
  int ck1 = 0, ck2 = 0;
  for (int i = 0; i < len; i++) {
    if (st[i] == '[') {
      obrace = i;
      ck1 = 1;
      break;
    }
  }
  for (int i = len - 1; i >= 0; i--) {
    if (st[i] == ']') {
      cbrace = i;
      ck2 = 1;
      break;
    }
  }
  if (obrace >= cbrace || (ck1 == 0 || ck2 == 0)) {
    cout << -1 << endl;
    return 0;
  }
  int flag1 = 0, flag2 = 0;
  for (int i = obrace + 1; i < cbrace; i++) {
    if (st[i] == ':') {
      fcolon = i;
      flag1 = 1;
      break;
    }
  }
  if (flag1 != 1) {
    cout << -1 << endl;
    return 0;
  }
  for (int i = cbrace - 1; i > fcolon; i--) {
    if (st[i] == ':') {
      lcolon = i;
      flag2 = 1;
      break;
    }
  }
  if (flag1 != 1 && flag2 != 1) {
    cout << -1 << endl;
    return 0;
  }
  int line = 0;
  if (obrace < cbrace && fcolon < lcolon) {
    for (int i = fcolon; i <= lcolon; i++) {
      if (st[i] == '|') line++;
    }
  } else {
    cout << -1 << endl;
    return 0;
  }
  long long int tot = line + 2 + 2;
  cout << tot << endl;
  return 0;
}
