#749. Matrix: Sum of the lower triangle (with the diagonal)
You are given a matrix of integers. **Sum of the lower triangle (with the diagonal)**.
### Input
The first line has n n, each of the next n lines has n integers (a square matrix).
### Output
The answer.
Examples
Input
4 4 3 -7 -9 6 -8 -7 6 1 -6 6 -1 -7 -9 6 -7 7
Output
-16
Input
3 3 9 7 7 -9 7 0 -5 6 1
Output
9
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.