array addition and multiplication in c

1//This program is for matrix addition by programiz.com
2#include <stdio.h>
3int main() {
4    int r, c, a[100][100], b[100][100], sum[100][100], i, j;
5    printf("Enter the number of rows (between 1 and 100): ");
6    scanf("%d", &r);
7    printf("Enter the number of columns (between 1 and 100): ");
8    scanf("%d", &c);
9
10    printf("\nEnter elements of 1st matrix:\n");
11    for (i = 0; i < r; ++i)
12        for (j = 0; j < c; ++j) {
13            printf("Enter element a%d%d: ", i + 1, j + 1);
14            scanf("%d", &a[i][j]);
15        }
16
17    printf("Enter elements of 2nd matrix:\n");
18    for (i = 0; i < r; ++i)
19        for (j = 0; j < c; ++j) {
20            printf("Enter element a%d%d: ", i + 1, j + 1);
21            scanf("%d", &b[i][j]);
22        }
23
24    // adding two matrices
25    for (i = 0; i < r; ++i)
26        for (j = 0; j < c; ++j) {
27            sum[i][j] = a[i][j] + b[i][j];
28        }
29
30    // printing the result
31    printf("\nSum of two matrices: \n");
32    for (i = 0; i < r; ++i)
33        for (j = 0; j < c; ++j) {
34            printf("%d   ", sum[i][j]);
35            if (j == c - 1) {
36                printf("\n\n");
37            }
38        }
39
40    return 0;
41}
42