#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
const long double eps = 1e-7;
const int inf = 1000000010;
const long long INF = 10000000000000010LL;
const int mod = 1000000007;
const int MAXN = 100010;
int n, m, k, u, v, x, y, t, a, b, ans, cnt, out;
string s;
bool f1, f2, f3, f4;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> s;
  n = s.size();
  for (int i = 0; i < n; i++) {
    if (!f1) {
      if (s[i] == '[') f1 = 1;
    }
    if (f1 && !f2) {
      if (s[i] == ':') f2 = 1;
    } else if (s[i] == ':' && f2) {
      ans = max(ans, cnt);
      f3 = 1;
    }
    if (f3 && s[i] == ']') {
      f4 = 1;
      out = max(out, ans);
    }
    if (f2 && s[i] == '|') cnt++;
  }
  if (!f4) return cout << -1 << '\n', 0;
  ;
  cout << out + 4 << endl;
  return 0;
}
