Adjacency Matrix in JAVA

public class AdjacencyMatrix {


    public static int[][] matrix = new int[20][20];

    public static void addEdge(int src, int dst)
    {
        matrix[src][dst]=1;
        matrix[dst][src]=1;
    }

    public static void printMatrix(int vertices)
    {
        for(int i=1; i<=vertices; i++){
            for(int j=1; j<=vertices; j++){
                System.out.print(matrix[i][j]+" ");
            }
            System.out.println();
        }
    }


    public static void main(String[] args) {
        // TODO code application logic here
        Scanner sc = new Scanner(System.in);
        int vertices, edges;

        System.out.println("Enter number of vertices: ");
        vertices = sc.nextInt();
        System.out.println("Enter number of edges: ");
        edges = sc.nextInt();
        int src, dst;
        for(int i=1; i<=edges; i++){
            System.out.println("Enter the source node: ");
            src = sc.nextInt();
            System.out.println("Enter the destination node: ");
            dst = sc.nextInt();
            addEdge(src, dst);
        }

        printMatrix(vertices);

    }

}