#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const int n_ = 1e5 + 1000;
const long double PI = acos(-1.0);
long long gcd(long long a, long long b) { return (a ? gcd(b % a, a) : b); }
long long power(long long a, long long n) {
  long long p = 1;
  while (n > 0) {
    if (n % 2) {
      p = p * a;
    }
    n >>= 1;
    a *= a;
  }
  return p;
}
long long power(long long a, long long n, long long mod) {
  long long p = 1;
  while (n > 0) {
    if (n % 2) {
      p = p * a;
      p %= mod;
    }
    n >>= 1;
    a *= a;
    a %= mod;
  }
  return p % mod;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  string s;
  cin >> s;
  long long pos1 = -1, pos2 = -1, pos_v, pos3 = -1, pos4 = -1;
  for (int i = 0; i < s.length(); i++) {
    if (s[i] == '[') {
      pos1 = i;
      break;
    }
  }
  for (int j = pos1 + 1; j < s.length(); j++) {
    if (s[j] == ':') {
      pos2 = j;
      break;
    }
  }
  for (int j = s.length() - 1; j >= 0; j--) {
    if (s[j] == ']') {
      pos4 = j;
      break;
    }
  }
  for (int j = pos4 - 1; j > pos2; j--) {
    if (s[j] == ':') {
      pos3 = j;
      break;
    }
  }
  long long count = 0;
  for (int i = pos2; i < pos3; i++) {
    if (s[i] == '|') count++;
  }
  if (pos1 == -1 || pos2 == -1 || pos3 == -1 || pos4 == -1)
    cout << -1 << "\n";
  else {
    cout << (4 + count) << "\n";
  }
}
