double Average( const apvector & A )
     {
         double Sum = 0.0;

         for( int i = 0; i < A.length( ); i++ )
             Sum += A[ i ];

         return Sum / A.length( ); // Precondition is A.length( ) > 0
     }

     int main( )
     {
         ifstream fin;
         int NumberOfItems;
         apvector A;
         int i;

         fin.open( "input.txt" );
         fin >> NumberOfItems;
         A.resize( NumberOfItems );

         for( i = 0; i < NumberOfItems; i++ )
             fin >> A[ i ];

         cout << "Average is " << Average( A ) << endl;

         return 0;
     }