Second multiply positive numbers pairwise and summed up from the last as to get maximum sum .
int j = n - 1 ; while ( j >= 0 && arr [ j ] > 0 ) { if ( j != 0 && arr [ j - 1 ] > 0 ) { sum = ( sum + ( arr [ j ] * arr [ j - 1 ] ) % Mod ) % Mod ; j -= 2 ; } else break ; }