#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return (b ? gcd(b, a % b) : a); }
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long MOD = 1e9 + 7;
int main() {
  std::ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  string s;
  cin >> s;
  long long l = -1, r = -1;
  for (long long i = 0; i < (long long)(s.size()); i++) {
    if (l < 0 && s[i] == '[') l = i;
    if (s[i] == ']') r = i;
  }
  if (l < 0 || r < 0 || l > r) {
    cout << -1;
  } else {
    long long l1 = -1, r1 = -1;
    for (long long i = l; i <= r; i++) {
      if (l1 < 0 && s[i] == ':') l1 = i;
      if (s[i] == ':') r1 = i;
    }
    if (l1 < 0 || r1 < 0 || l1 >= r1) {
      cout << -1;
    } else {
      long long cnt = 4;
      for (long long i = l1; i <= r1; i++) {
        if (s[i] == '|') cnt++;
      }
      cout << cnt;
    }
  }
}
