#include <cstdio>
#include <algorithm>
#pragma GCC optimize(2)
using namespace std;
#ifdef ONLINE_JUDGE
#define getchar getchar_unlocked
#endif
namespace FastIO {
    char write_cache[40];
    template <class T>
    inline const T read() noexcept
    {
        T x(0);
        char ch(getchar());
        bool f(0);
        while (ch < '0' || ch > '9')
            f ^= ch == '-', ch = getchar();
        while (ch >= '0' && ch <= '9')
            x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
        return f ? -x : x;
    }
    template <class T>
    inline const void read(T &x) noexcept
    {
        x = 0;
        char ch(getchar());
        bool f(0);
        while (ch < '0' || ch > '9')
            f ^= ch == '-', ch = getchar();
        while (ch >= '0' && ch <= '9')
            x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
        x = f ? -x : x;
    }
    template <class T, class... P>
    inline const void read(T &x, P &...ark) noexcept
    {
        x = 0;
        char ch(getchar());
        bool f(0);
        while (ch < '0' || ch > '9')
            f ^= ch == '-', ch = getchar();
        while (ch >= '0' && ch <= '9')
            x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
        x = f ? -x : x;
        read(ark...);
    }
    template <class T>
    inline const void readu(T &x) noexcept
    {
        x = 0;
        char ch(getchar());
        bool f(0);
        while (ch < '0' || ch > '9')
            ch = getchar();
        while (ch >= '0' && ch <= '9')
            x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
    }
    template <class T>
    inline const T readu() noexcept
    {
        T x(0);
        char ch(getchar());
        bool f(0);
        while (ch < '0' || ch > '9')
            ch = getchar();
        while (ch >= '0' && ch <= '9')
            x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
        return x;
    }
    template <class T, class... P>
    inline const void readu(T &x, P &...ark) noexcept
    {
        x = 0;
        char ch(getchar());
        bool f(0);
        while (ch < '0' || ch > '9')
            ch = getchar();
        while (ch >= '0' && ch <= '9')
            x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
        readu(ark...);
    }
    template <class T>
    inline const void readArr(T *begin, T *end) noexcept
    {
        while (begin < end)
        {
            *begin = 0;
            char ch(getchar());
            bool f(0);
            while (ch < '0' || ch > '9')
                f ^= ch == '-', ch = getchar();
            while (ch >= '0' && ch <= '9')
                *begin = (*begin << 1) + (*begin << 3) + (ch ^ 48), ch = getchar();
            *begin = f ? -*begin : *begin;
        }
    }
    template <class T>
    inline const void readArr(T *begin, int cnt) noexcept
    {
        while (cnt--)
        {
            read(*begin);
            ++begin;
        }
    }
    template <class T>
    inline const void write(T x) noexcept
    {
        if (x < 0)
            putchar('-'), x = -x;
        int cnt = 0;
        while (x)
            write_cache[cnt++] = x % 10 ^ 48, x /= 10;
        if (!cnt)
            putchar('0');
        else
            while (cnt--)
                putchar(write_cache[cnt]);
    }
    template <char end = ' ', class T, class... ARK>
    inline const void write(T &x, ARK &...ark) noexcept
    {
        write(x);
        putchar(end);
        write(ark...);
    }
    template <char end = '\n', class T>
    inline const void println(T x) noexcept
    {
        if (x < 0)
            putchar('-'), x = -x;
        int cnt = 0;
        while (x)
            write_cache[cnt++] = x % 10 ^ 48, x /= 10;
        if (!cnt)
            putchar('0');
        else
            while (cnt--)
                putchar(write_cache[cnt]);
        putchar(end);
    }
    template <char sep = ' ', char endl = '\n', class T>
    inline const void writeArr(T *begin, T *end) noexcept
    {
        while (begin < end)
            write(*begin), putchar(sep), ++begin;
        putchar(endl);
    }
    template <char sep = ' ', char end = '\n', class T>
    inline const void writeArr(T *arr, int cnt)
    {
        while (cnt--)
        {
            write(*arr);
            putchar(sep);
            ++arr;
        }
        putchar(end);
    }
}
using namespace FastIO;
inline int _max(int x, int y) {
	return (x > y) ? x : y;
}
inline int _min(int x, int y) {
	return (x < y) ? x : y;
}
const int N = 1005, INF = 1e9 + 7;
int a, b, n, g[N][N], ans = INF, f1[N][N], f2[N][N];
int main() {
	read(a, b, n);
	for (register int i = 0; i < a; ++ i )
		for (register int j = 0; j < b; ++ j ) {
			read(g[i][j]);
			f1[i][j] = g[i][j];
			f2[i][j] = g[i][j];
		}
	for (register int k = 0; k < n - 1; ++ k )
        for (register int i = 0; i < a - 1; ++ i )
            for (register int j = 0; j < b - 1; ++ j ) {
                f1[i][j] = _max(g[i][j], _max(f1[i + 1][j + 1], _max(f1[i + 1][j], f1[i][j + 1])));
                f2[i][j] = _min(g[i][j], _min(f2[i + 1][j + 1], _min(f2[i + 1][j], f2[i][j + 1])));
            }
    for (register int i = 0; i <= a - n; i ++ )
        for (register int j = 0; j <= b - n; j ++ )
            ans = _min(ans, f1[i][j] - f2[i][j]);
    println(ans);
    return 0;
}