#include <bits/stdc++.h>
using namespace std;
const int mod = 998244353;
long long qpow(long long x, long long y) {
  long long s = 1;
  while (y) {
    if (y & 1) s = s * x % mod;
    x = x * x % mod;
    y >>= 1;
  }
  return s;
}
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  return x * f;
}
long long inve(long long x) {
  return x == 1 ? 1 : (mod - mod / x) * inve(mod % x) % mod;
}
char s[500005];
int a[500005];
int num[5];
int main() {
  scanf("%s", s);
  int len = strlen(s), k = 0;
  for (int i = 0; i < len; i++) {
    if ((int)s[i] == 91 || (int)s[i] == 58 || (int)s[i] == 93 ||
        (int)s[i] == 124)
      a[k++] = (int)s[i];
    if ((int)s[i] == 91) num[1]++;
    if ((int)s[i] == 58) num[2]++;
    if ((int)s[i] == 124) num[3]++;
    if ((int)s[i] == 93) num[4]++;
  }
  if (num[4] < 1 || num[1] < 1 || num[2] < 2) return cout << -1 << "\n", 0;
  int i = 0;
  k = k - 1;
  while (a[i] != 91) i++;
  while (a[k] != 93) k--;
  while (a[i] != 58) i++;
  while (a[k] != 58) k--;
  if (i >= k) return cout << -1 << "\n", 0;
  int ans = 4;
  for (; i < k; i++)
    if (a[i] == 124) ans++;
  cout << ans << "\n";
  return 0;
}
