#include <bits/stdc++.h>
using namespace std;
const long long INF = LLONG_MAX;
const long long base = 1e9;
const double PI = acos(-1);
const long long MOD = 1e9 + 7;
const long long N = 1e5 + 10;
void solve();
int main() {
  ios_base ::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
  return 0;
}
void solve() {
  string s;
  cin >> s;
  long long n = s.size(), mark, a1 = 0, a2 = 0, a3 = 0, a4 = 0, sup = -1;
  for (long long i = 0; i < n; ++i) {
    if (s[i] == ']') {
      sup = i;
    }
  }
  if (sup == -1) {
    cout << "-1\n";
    return;
  }
  for (long long i = 0; i <= sup; ++i) {
    if (!a1 and s[i] == '[') {
      a1 = 1;
    }
    if (a1 and s[i] == ':') {
      if (a2) {
        a3 = 1;
      } else {
        a2 = 1;
      }
    }
    if (a3 and s[i] == ']') {
      a4 = 1;
    }
    if (s[i] == ':') {
      mark = i;
    }
  }
  if (!a4) {
    cout << "-1\n";
  } else {
    a1 = 0, a2 = 0;
    long long ans = 0;
    for (long long i = 0; i < mark; ++i) {
      if (!a1 and s[i] == '[') {
        a1 = 1;
        ++ans;
      }
      if (a1 and !a2 and s[i] == ':') {
        a2 = 1;
        ++ans;
      }
      if (a2 and s[i] == '|') {
        ++ans;
      }
    }
    cout << ans + 2 << "\n";
  }
  return;
}
