C5-E cbj

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#include <time.h>
long long mat[4][4] = { 0 }, submat[3][3] = { 0 };
void copy(int x, int y){
    int i, j, p = 0, q;
    for(i = 0; i < 4; i++){
        if(i == x){
            continue;
        }
        q = 0;
        for(j = 0; j < 4; j++){
            if(j == y){
                continue;
            }
            submat[p][q] = mat[i][j];
            q++;
        }
        p++;
    }
}
long long det3(){
    return ((submat[0][0] * submat[1][1] * submat[2][2]) + (submat[1][0] * submat[2][1] * submat[0][2]) + (submat[2][0] * submat[0][1] * submat[1][2])) - ((submat[2][0] * submat[1][1] * submat[0][2]) + (submat[1][0] * submat[0][1] * submat[2][2]) + (submat[0][0] * submat[2][1] * submat[1][2]));
}
int main(){
    int i, j;
    for(i = 0; i < 4; i++){
        for(j = 0; j < 4; j++){
            scanf("%lld", &(mat[i][j]));
        }
    }
    copy(0, 1);//M1,2
    printf("%lld\n", det3());
    copy(3, 2);//M4,3
    printf("%lld\n", det3());
    copy(2, 2);//M3,3
    printf("%lld\n", det3());
    copy(0, 3);//M1,4
    printf("%lld\n", det3());
    copy(1, 3);//M2,4
    printf("%lld\n", det3());
    copy(2, 2);//M3,3
    printf("%lld\n", det3());
    copy(1, 1);//M2,2
    printf("%lld\n", det3());
    copy(3, 0);//M4,1
    printf("%lld\n", det3());
    return 0;
}