Find sum of upper and lower triangular matrix

Exercise 3. WAP to Find sum of upper and lower triangular matrix. 1

#include<stdio.h>
void main()
{
    int a[3][3], i, j, upper=0, lower=0;
    printf("Enter 3x3 matrix:");
    for(i=0;i<=2;i++)
    {
        for(j=0;j<=2;j++)
        {
            scanf("%d",&a[i][j]);
        }
    }
    
    printf("\nInput matrix is:\n");
    for(i=0;i<=2;i++)
    {
        for(j=0;j<=2;j++)
        {
            printf("%d  ",a[i][j]);
        }
        printf("\n");
    }
    
    for(i=0;i<=2;i++) //row
    {
        for(j=0;j<=2;j++) //col
        {
            if(i<=j)
                upper = upper +a[i][j];
            if(i>=j)
                lower = lower+a[i][j];
        }
    }
    printf("\nSum of Upper triangular matrix = %d",upper);
    printf("\nSum of Lower triangular matrix = %d",lower);
}