Why is my input not accepting 0?

 System.out.println("Special Teams Represent Teams  entering only 1 event");
        System.out.println(" If there are no Special Teams or Individuals Enter 0 when the amount is asked");
        // the start of special teams
        // number of special teams
        int SpecTeamNo;
        System.out.println("-----Special_Teams-----");
        System.out.println("You have " + (4 - teamNo) + " available for special teams");
        do {
            System.out.println("Enter Amount of Teams Entering only 1 EVENT");
            SpecTeamNo = scan.nextInt();
        } while (SpecTeamNo > 4 - teamNo);


        String[] SpecTeamName = new String[SpecTeamNo];
        String[] STevent = new String[1];
        int[] SpecTeamScore = new int[SpecTeamNo];
        int sTeamRank;
// condition checking for number of special teams
        //skip if 0
        if (SpecTeamNo == 0) {
        } else {
            // event for special team
            for (int i = 0; i < 1; i++) {
                System.out.println("Enter Event Name " + (i + 1) + " for the teams");
                STevent[i] = scan.next();
            }

        }
// name and rank of special teams
        for (
                int i = 0;
                i < SpecTeamNo; i++) {
            System.out.println("Enter Name of team " + (i + 1));
            SpecTeamName[i] = scan.next();
        }

            for (int a = 0; a < 1; a++) {
                for (int i=0; i < SpecTeamNo; i++) {
                System.out.println("Enter rank of the team "+SpecTeamName[i]+" on the event");
                sTeamRank = scan.nextInt();
                int stRank = 0;
                // scoring system for special team
                switch (sTeamRank) {
                    case 3:
                        stRank = 60;
                        break;
                    case 2:
                        stRank = 80;
                        break;
                    case 1:
                        stRank = 100;
                        break;
                }
                if (sTeamRank == 0 || sTeamRank >= 4) {
                    System.out.println("This team will not be awarded points");
                } else {
                    SpecTeamScore[i] += stRank;
                    System.out.println(stRank + " points is granted for this event");
                }

                if (scan.hasNextLine()) {
                    scan.nextLine();
                }
            }
            int topSTScore = 0; // this will be used to find the highest value score
            int topSteam = -1; // and this will be the index of the team
            for (int i = 0; i < SpecTeamNo; i++) {
                if (SpecTeamScore[i] > topSTScore) {
                    topSTScore = SpecTeamScore[i]; // the highest score (up to now)
                    topSteam = i; // save the team number for the one with the highest score
                }
            }
            System.out.println(SpecTeamName[topSteam] + " is the winner, with a score of " + topSTScore);
        }

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index -1 out of bounds for length 0