#include <bits/stdc++.h>
using namespace std;
long long fo = INT_MAX, lc = 0, fco = INT_MAX, lco = 0;
int32_t main() {
  string s;
  cin >> s;
  long long n = s.size(), ans = 0, tmp = 0, tmp2 = 0;
  for (long long i = 0; i < n; i++) {
    if (s[i] == '[') {
      fo = min(fo, i);
    }
    if (s[i] == ']' and fo != INT_MAX and lco != fco and fco != INT_MAX) {
      lc = max(lc, i);
      ans += tmp2;
      tmp2 = 0;
    }
    if (s[i] == ':' and fo != INT_MAX) {
      fco = min(fco, i);
      lco = max(lco, i);
      if (lco != fco) {
        tmp2 += tmp;
        tmp = 0;
      }
    }
    if (s[i] == '|' and fco != INT_MAX) {
      tmp++;
    }
  }
  if (fco == lco or fco == INT_MAX or lc == 0) {
    cout << "-1";
    return 0;
  }
  cout << ans + 4;
}
