#include <bits/stdc++.h>
using namespace std;
const int seed = 131;
const int maxn = 1e6 + 5;
const int mod = 1e9 + 7;
char str[maxn];
int main() {
  scanf("%s", str);
  int len = strlen(str);
  int num = 0;
  int pos1 = -1;
  int pos2 = -1;
  for (int i = 0; str[i]; i++) {
    if (str[i] == '[') {
      pos1 = i;
      break;
    }
  }
  for (int i = len - 1; i >= 0; i--) {
    if (str[i] == ']') {
      pos2 = i;
      break;
    }
  }
  int pos3 = -1;
  int pos4 = -1;
  for (int i = pos1 + 1; i < pos2; i++) {
    if (str[i] == ':') {
      pos3 = i;
      break;
    }
  }
  for (int i = pos2 - 1; i > pos3; i--) {
    if (str[i] == ':') {
      pos4 = i;
      break;
    }
  }
  for (int i = pos3; i <= pos4; i++) {
    if (str[i] == '|') num++;
  }
  if (pos1 == -1 || pos2 == -1 || pos3 == -1 || pos4 == -1)
    printf("-1\n");
  else
    printf("%d\n", num + 4);
  return 0;
}
