Assignment Problem

Given an N x N matrix (1 <= N <= 150) with each element being an integer in
the range 1..1,000,000,000, choose N of these elements such that no two are
in the same row, no two are in the same column, and their total sum is
minimized.

PROBLEM NAME: assign

INPUT FORMAT:

* Line 1: The single integer N.

* Lines 2..N+1: Line i+1 contains N space-separated integers denoting
        the elements of row i.

SAMPLE INPUT:

3
7 9 6
3 2 9
9 5 1

OUTPUT FORMAT:

* Line 1: A single integer representing the minimum possible sum.

SAMPLE OUTPUT:

10

OUTPUT DETAILS:

The best solution is to take the 7, the 2, and the 1.