Segment Tree - Multiple Update

Light Switching

Farmer John tries to keep the cows sharp by letting them play with intellectual toys. One of the larger toys is the lights in the barn. Each of the n (2n105) cow stalls conveniently numbered from 1 to n has a colorful light above it.

At the beginning of the evening, all the lights are off. The cows control the lights with a set of n pushbutton switches that toggle the lights; pushing switch i changes the state of light i from off to on or from on to off.

The cows read and execute a list of m (1m105) operations expressed as one of two integers (0operation1).

The first kind of operation (denoted by a 0 command) includes two subsequent integers Si and Ei (1SiEin) that indicate a starting switch and ending switch. They execute the operation by pushing each pushbutton from Si through Ei inclusive exactly once.

The second kind of operation (denoted by a 1 command) asks the cows to count how many lights are on in the range given by two integers Si and Ei (1SiEin) which specify the inclusive range in which the cows should count the number of lights that are on.

Help Farmer John ensure the cows are getting the correct answer by processing the list and producing the proper counts.


The first line contains two integers n and m. Each of the next m lines represents an operation with three integers: operation, Si and Ei.


For each operation of the second kind print the answer as an integer on a single line.

Time limit 1 second
Memory limit 128 MiB
Input example #1
4 5
0 1 2
0 2 4
1 2 3
0 2 4
1 1 4
Output example #1