#include <stdio.h>

int mat_det(int mat[4][4])
{
    int a = mat[0][0];
    int b = mat[0][1];
    int c = mat[0][2];
    int d = mat[0][3];
    int e = mat[1][0];
    int f = mat[1][1];
    int g = mat[1][2];
    int h = mat[1][3];
    int i = mat[2][0];
    int j = mat[2][1];
    int k = mat[2][2];
    int l = mat[2][3];
    int m = mat[3][0];
    int n = mat[3][1];
    int o = mat[3][2];
    int p = mat[3][3];

    return a * f * k * p - a * f * l * o - a * g * j * p + a * g * l * n
    + a * h * j * o - a * h * k * n - b * e * k * p + b * e * l * o
    + b * g * i * p - b * g * l * m - b * h * i * o + b * h * k * m
    + c * e * j * p - c * e * l * n - c * f * i * p + c * f * l * m
    + c * h * i * n - c * h * j * m - d * e * j * o + d * e * k * n
    + d * f * i * o - d * f * k * m - d * g * i * n + d * g * j * m;
}