#include<stdio.h>

// Inserts an element. Returns the number of new elements.
int insert(int arr[], int len, int num, int key) {
    int i;

    if (len == key) {
        arr[key] = num;
        return len+1;
    }
    else {
        for (i=len-1; i>=key; i--) {
            // Shifting elements to right
            arr[i+1] = arr[i];

            // Stop when key is reached.
            if (i == key) {
                arr[key] = num;
                return len+1;
            }
        }
    }

    return len;
}

// Inserts an element. Returns the number of new elements.
int delete(int arr[], int len, int key) {
    int i;

    for (i=key; i<len; i++) {
        arr[i] = arr[i+1];
    }

    return len-1;
}

// Display a menu
int menu() {
    int option;
    printf("\nSelect an option:\n 1) Insert an element\n 2) Delete an element\n 3) Exit\nAns: ");
    scanf("%d", &option);
    return option;
}

int display(int arr[], int len) {
    int i;
    for (i = 0; i < len; i++)
        printf("%d  ",arr[i]);
}

// Driver Code
int main() {
    int arr[20] = {12, 16, 20, 40, 50, 70};
    int len = 6, num, key;

    while (1) {
        printf("\nArray: ");
        display(arr, len);

        switch (menu()) {
            case 1:
                printf("What do you want to insert? : ");
                scanf("%d", &num);
                printf("At which position do you want to insert %d? : ", num);
                scanf("%d", &key);
                len = insert(arr, len, num, key);
            break;
            case 2:
                printf("Enter the position of the element that you want to delete: ");
                scanf("%d", &key);
                len = delete(arr, len, key);
            break;
            case 3: return 0;
            default: printf("\nInvalid option\n");
        }
    }
}