#include <bits/stdc++.h>
using namespace std;
const double PI = 2.0 * acos(0.0);
const int MOD = 1e9 + 7;
const long long oo = 1e9 + 7;
long long GCD(long long a, long long b) { return !b ? a : GCD(b, a % b); }
int main() {
  string str;
  cin >> str;
  int l, r;
  l = r = -1;
  for (long long i = 0; i < (int)str.size(); i++) {
    if (str[i] == '[' && l == -1) l = i;
    if (str[i] == ']') r = i;
  }
  if (l > r || l == -1 || r == -1) {
    puts("-1");
    return 0;
  }
  int a, b;
  a = b = -1;
  for (long long i = l; i < r + 1; i++) {
    if (str[i] == ':' && a == -1)
      a = i;
    else if (str[i] == ':')
      b = i;
  }
  if (a == -1 || b == -1) {
    puts("-1");
    return 0;
  }
  int cnt = 4;
  for (long long i = a; i < b + 1; i++)
    if (str[i] == '|') ++cnt;
  cout << cnt << '\n';
  return 0;
}
