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  1. Practice
  2. Mathematics
  3. Fundamentals
  4. Filling Jars

Filling Jars

Animesh has empty candy jars, numbered from to , with infinite capacity. He performs operations. Each operation is described by integers, , , and . Here, and are indices of the jars, and is the number of candies to be added inside each jar whose index lies between and (both inclusive). Can you tell the average number of candies after operations?

Input Format

The first line contains two integers, and , separated by a single space.
lines follow; each of them contains three integers, , , and , separated by spaces.

Constraints



Output Format

A single line containing the average number of candies across jars, rounded down to the nearest integer.

Note: Rounded down means finding the greatest integer which is less than or equal to the given number. E.g. 13.65 and 13.23 are rounded down to 13, while 12.98 is rounded down to 12.

Sample Input

5 3
1 2 100
2 5 100
3 4 100

Sample Output

160

Explanation

Initially each of the jars contains 0 candies 

0 0 0 0 0

First operation: 

100 100 0 0 0

Second operation: 

100 200 100 100 100

Third operation: 

100 200 200 200 100

Total = 800, Average = 800/5 = 160