#include<stdio.h>
int
main ()
{

int n, i, j;

printf ("Matrix Size:");

scanf ("%d", &n);

printf ("\nMatrix Element:");

int mtrx[n][n];

for (i = 0; i < n; i++)
    {

for (j = 0; j < n; j++)
	{

scanf ("%d", &mtrx[i][j]);

}

}

int s = 0;

for (i = 0; i < n; i++)
    {

for (j = 0; j < n; j++)
	{

if (j < n - i)
	    {

s += mtrx[i][j];

}

}

}

printf ("Sum = %d\n", s);

return 0;

}