static int spoctiNuloveRadky( int[][] m ) {
     int pocet = 0;
     for( int i = 0; i < m.length; i++ ) {
        boolean jeNulovy = true;
        for( int j = 0; j < m[i].length; j++ ) {
           if( m[i][j] != 0 ) {
              jeNulovy = false;
              break;
           }
        }
        if( jeNulovy ) {
           pocet++;
        }
     }
     return pocet;
  }