Stergere coloana dintr-o matrice

#include <fstream>
using namespace std;
int main()
{
        int n, m, l, a[100][100], i, j, c;
        ifstream f("mat.IN");
        f >> l >> c >> n >> m;
        for(i = 1; i <= n; i++) {
                for(j = 1; j <= m; j++) {
                        f >> a[i][j];
                }
        }
        f.close();
        ofstream g("mat.out");
        g << "Afisarea normala a matricei:\n\n";
        for(i = 1; i <= n; i++) {
                for(j = 1; j <= m; j++) {
                        g << a[i][j] << " ";
                }
                g << endl;
        }
        g << "\n\nMatricea finala:";
        for(i = l + 1; i <= n; i++) {
                for(j = 1; j <= m; j++) {
                        a[i-1][j] = a[i][j];
                }
                g << endl;
        }
        n--;
        for(i = 1; i <= n; i++) {
                for(j = c + 1; j <= m; j++) {
                        a[i][j-1] = a[i][j];
                }
        }
        m--;
        for(i = 1; i <= n; i++) {
                for(j = 1; j <= m; j++) {
                        g << a[i][j] << " ";
                }
                g<< endl;
        }
        for(i = 1; i <= n; i++) {
                for(j = c + 1; j <= m; j++) {
                        a[i][j-1] = a[i][j];
                }
        }
        return 0;
}