for (i = 0; i < n; i++)
{
    for (j = 0; j < m; j++)
    {
        if (a[i] == b[j])
        {
            goto found;
        }
    }

    /* didnt find any common element */
}

found:
    /* got one: a[i] == b[i] */
    ...



"Code involving a goto can always be written w/o one... the example above becomes..."

int found = 0;

for (i = 0; i < n && !found; i++)
{
    for (j = 0; j < m && !found; j++)
    {
        if (a[i] == b[j])
        {
            found = 1;
        }
    }
}

if (found)
    /* got one: a[i-1] == b[j-1] */
...

else
    /* didnt find any common element */
...