[pavel@Lightning-Squirrel homework1]$ javac Matrix.java 
Matrix.java:19: variable A might not have been initialized
        A[i][j] = a;
        ^
Matrix.java:12: unreported exception java.io.IOException; must be caught or declared to be thrown
    n = (int) br.read();
                     ^
Matrix.java:14: unreported exception java.io.IOException; must be caught or declared to be thrown
    m = (int) br.read();
                     ^
3 errors
[pavel@Lightning-Squirrel homework1]$