iva_frame.c

#include <stdio.h>

int main(int argc, char const *argv[])
{
    int n;
    scanf("%d", &n);

    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            if (i == 0 || i == n - 1 || j == 0 || j == n - 1) {
                printf("-");
            }
            else if (i == 1 || i == n - 2 || j == 1 || j == n - 2) {
                printf("+");
            } else {
                printf(" ");
            }
        }
        printf("\n");

    }

    return 0;
}