#include <stdlib.h>
#include <stdio.h>
#include <string.h>

int m[5][5] =
{
    { 1,2,3,4,5},
    { 6,7,8,9,10},
    { 11,12,13,14,15},
    { 16,17,18,19,20},
    { 21,22,23,24,25}
};

void out_matrix(int r[4][5])
{
    for(int i = 0; i < 4; ++i)
    {
        for(int j = 0; j < 5; ++j)
        {
            printf("%2d  ",r[i][j]);
        }
        puts("");
    }
}

int main()
{
    typedef int reduced_matrix[4][5];
    reduced_matrix * r = (reduced_matrix*)(m+1);

    for(int i = 0; i < 4; ++i)
    {
        for(int j = 0; j < 5; ++j)
        {
            printf("%2d  ",(*r)[i][j]);
        }
        puts("");
    }
    puts("----\n");
    out_matrix(m+1);
}