First multiply negative numbers pairwise and sum up from starting as to get maximum sum .
int i = 0 ; while ( i < n && arr [ i ] < 0 ) { if ( i != n - 1 && arr [ i + 1 ] <= 0 ) { sum = ( sum + ( arr [ i ] * arr [ i + 1 ] ) % Mod ) % Mod ; i += 2 ; } else break ; }