using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace minmark
{
    class Program
    {
        static void Main(string[] args)
        {
            string inFile = System.IO.File.ReadAllText("geo.in");
            string[] rows = inFile.Split(new char[] { '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries);
            int rowsCount = int.Parse(rows[0].Split(' ')[0]);
            int colCount = int.Parse(rows[0].Split(' ')[1]);
            int num = int.Parse(rows[0].Split(' ')[2]);
            int[,] table = new int[rowsCount, colCount];
            for (int i = 0; i < rowsCount; i++)
            {
                for (int j = 0; j < colCount; j++)
                {
                    table[i, j] = int.Parse(rows[i + 1].Split(' ')[j]);
                }
            }

            int miniTableSize = -1;
            for (int i = 0; i < table.GetLength(0); i++)
            {
                for (int j = 0; j < table.GetLength(1); j++)
                {
                    for (int m = i; m < table.GetLength(0); m++)
                    {
                        for (int n = j; n < table.GetLength(1); n++)
                        {
                            int miniTableSum = 0;
                            for (int k = i; k <= m; k++)
                            {
                                for (int l = j; l <= n; l++)
                                {
                                    miniTableSum += table[k, l];
                                }
                            }
                            if (miniTableSum >= num)
                            {
                                int mTSize = (m - i + 1) * (n - j + 1);
                                if (mTSize < miniTableSize || miniTableSize == -1)
                                {
                                    miniTableSize = mTSize;
                                }
                            }
                        }
                    }
                }
            }


            System.IO.File.WriteAllText("geo.out", miniTableSize.ToString());
        }
    }
}