graph - Runtime error in java code -

i'm creating program assignment takes input system.in in following format:

inky pinky blinky clyde luigi mario bowser 0 2 1 2 5 6 3 5 2 4 4 5 2 3 1 4 closefriends 1 2 4 

where first line persons, numbers friendships.

the program checks whether or not people listed in last line in "close friendship", they're friends.

i represent network incident matrix, , passes every test on test site use, except one, fails "runtime error". know it's not exception, because catching exceptions nothing error, while catching errors does.

here's code:

public class closefriends {     // contains edges represented incident matrix     private static boolean edges[][];      // adds directed edge between v1 , v2     // method sorts edges reduce space used      public static void addedge(int v1, int v2) {         if (v1 > v2) {             edges[v1][v2] = true;         }         else {             edges[v2][v1] = true;         }     }      // creates graph v vertices     public static void createvertices(int v) {         edges = new boolean[v][v];     }      // checks if edge exists between v1 , v2     public static boolean isfriends(int v1, int v2) {         if (v1 > v2) {             return edges[v1][v2];         }         else {             return edges[v2][v1];         }     }      // checks if arraylist of vertices close friends     public static void closefriends(arraylist<integer> vertices) {         int count = 0;         int size = vertices.size();          (int = 0; < size; i++) {             (int j = + 1; j < size; j++) {                 if (isfriends(vertices.get(i), vertices.get(j))) {                     count++;                 }             }         }         // clique should contain n*(n-1)/2 edges connected         if (count == (size * (size - 1) / 2)) {             system.out.println("yes");         }         else {             system.out.println("no");         }     }      public static void main(string[] args) throws ioexception {         bufferedreader in = new bufferedreader(new inputstreamreader(system.in));         stringtokenizer st = new stringtokenizer(in.readline());          // count vertices, , create amount         int v = 0;         while (st.hasmoretokens()) {             st.nexttoken();             v++;         }         createvertices(v);          arraylist<integer> friends = new arraylist<integer>();          // while system.in has read         while (in.ready()) {             // read line , add edges based on input, or run algorithm             string edge = "";              edge = in.readline();              if (edge != null) {                 st = new stringtokenizer(edge);                 if (!edge.startswith("closefriends")) {                     addedge(integer.parseint(st.nexttoken()), integer.parseint(st.nexttoken()));                 }                 else {                     st.nexttoken();                     while (st.hasmoretokens()) {                         friends.add(integer.parseint(st.nexttoken()));                     }                 }             }         }         closefriends(friends);     } } 

thanks!