#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;
long long int M = 1e9 + 7;
long long int MOD = 998244353;
const double PI = 3.141592653589793238460;
bitset<N> bs;
bitset<512> bb[512];
long long int power(long long int a, long long int b) {
  long long int res = 1;
  if (a == 0) return 0;
  if (a == 1) return 1;
  for (; b > 0; b >>= 1) {
    if (b & 1) {
      res = (res * a);
      if (res > M) res %= M;
    }
    a = (a * a);
    if (a > M) a = a % M;
  }
  return res;
}
bool check(long long int arr[], int k, long long int m, long long int n) {
  long long int sum = 0;
  for (int j = 0; j < n; j++) {
    sum += max(0ll, arr[j] - (j) / (k));
  }
  if (sum >= m) {
    return true;
  }
  return false;
}
int main() {
  string s;
  cin >> s;
  bool open = 0, close = 0, colon1 = 0, colon2 = 0;
  int cnt = 0;
  int oi = -1, ci = -1, oc = -1, cc = -1;
  for (int i = 0; i < s.length(); i++) {
    if (s[i] == '[' && !open) {
      open = 1;
      cnt++;
      oi = i;
    } else if (s[i] == ':' && colon1 == 0 && open == 1) {
      colon1 = 1;
      cnt++;
      oc = i;
    } else if (s[i] == '|' && open == 1 && colon1 == 1)
      cnt++;
  }
  for (int i = s.length() - 1; i >= 0; i--) {
    if (s[i] == ']' && close == 0) {
      close = 1;
      cnt++;
      ci = i;
    } else if (s[i] == ':' && close == 1 && colon2 == 0) {
      colon2 = 1;
      cnt++;
      cc = i;
      break;
    } else if (s[i] == '|')
      cnt--;
  }
  if (open && close && colon1 && colon2 && ci > oi && cc > oc)
    cout << cnt << "\n";
  else
    cout << -1;
}
