#include<bits/stdc++.h>

using namespace std;

/// Typedef
typedef long long ll;

#define sc1(a) scanf("%lld",&a)
#define sc2(a,b) scanf("%lld %lld",&a,&b)

#define pf1(a) printf("%lld\n",a)
#define pf2(a,b) printf("%lld %lld\n",a,b)

#define mx 10000007
#define mod 100000007
#define PI acos(-1.0)

#define mx1 5005

int dr[] = {-2,-2,-1,-1,1,1,2,2};
int dc[] = {-1,1,-2,2,-2,2,-1,1};

string arr;

void calculate(string &arr, const string &ch){

    auto pos = arr.find(ch);

    if (pos == string::npos) {
        cout << -1 << endl;
        exit(0);
    }
    arr.erase(0, pos + 1);

}


int main()
{
    ll num, m, tc, t = 1;

   // freopen("/media/morol/574830c2-aaf8-40d8-9a94-7a029a2e831f/coding/clion/p1/output.txt", "w", stdout);

   string arr;
   cin >> arr;

   calculate(arr, "[" );
   calculate(arr, ":" );
   reverse(arr.begin(), arr.end());
   calculate(arr, "]");
   calculate(arr, ":");

   ll ans = 0;
   for(ll i = 0; i < arr.size(); i++){
       if(arr[i] == '|') ans++;
   }

   pf1(ans + 4);

    return 0;

}