#include<stdio.h>
void main()
{
    int a[10][10],i,j,sum=0,m,n;
    printf("\nEnter the row and column of matrix: ");
    scanf("%d%d",&m,&n);
    printf("\nEnter the elements of matrix: ");
    for(i=0; i<m; i++)
        for(j=0; j<n; j++)
            scanf("%d",&a[i][j]);
    printf("\nThe matrix is\n");
    for(i=0; i<m; i++)
        {
            printf("\n");
            for(j=0; j<m; j++)
                {
                    printf("%d\t",a[i][j]);
                }
        }
    for(i=0; i<m; i++)
        {
            for(j=0; j<n; j++)
                {
                    if(i==j)
                        sum=sum+a[i][j];
                }
        }
    printf("\nSum of the diagonal elements of a matrix is: %d",sum);
}