Function for push down operation on the segment tree
static void pushDown ( Vector < Integer > sum , Vector < Integer > add , int rt , int ln , int rn ) { if ( add . get ( rt ) != 0 ) { add . set ( rt << 1 , add . get ( rt ) ) ; add . set ( rt << 1 | 1 , add . get ( rt ) ) ; sum . set ( rt << 1 , sum . get ( rt << 1 ) + add . get ( rt ) * ln ) ; sum . set ( rt << 1 | 1 , sum . get ( rt << 1 1 ) + add . get ( rt ) * rn ) ; add . set ( rt , 0 ) ; } }