EX6

#include <stdio.h>

int prim(int nr)
{
    int i, ok = 1;

    for(i = 2; i <= nr/2; i++)
        if(nr % i == 0)
            ok = 0;

    if(ok == 1)
        return 1;
    else
        return 0;
}

int cautareprim(int nr, int op)
{
    int i = nr, nrprim = 1;

    for(;;)
    {
        if(i >= 1)
        {
            if(prim(i) == 0 && op == 1)
                i++;
            else if(prim(i) == 0 && op == 0)
                i--;
            else
                break;
        }
        else
            break;
    }

    return i;
}

int main()
{
    int i, nr, dist, prs, prd;

    scanf("%d", &nr);

    while(nr >= 0)
    {
        if(prim(nr))
            scanf("%d", &nr);
        else
        {
            prs = cautareprim(nr, 0);
            prd = cautareprim(nr, 1);
            if(prs == 1 && prd != 1)
                printf("%d\n", prd);
            else if(prs != 1 && prd == 1)
                printf("%d\n", prs);
            else
            {
                if((nr - prs) == (prd - nr))
                    printf("%d %d\n", prs, prd);
                else if((nr - prs) > (prd - nr))
                    printf("%d\n", prd);
                else if((nr - prs) < (prd - nr))
                    printf("%d\n", prs);
            }

            scanf("%d", &nr);
        }
    }

    return 0;
}