from re import match

components=[]
for _ in range(int(input().strip())):
    cords = input().split()
    matching_components=[]
    for i in range(len(components)-1,-1,-1):
        if cords[0] in components[i][0] or cords[1] in components[i][1]:
            matching_components.append(i)
    if matching_components == []:
        components.append((set(cords[0]),set(cords[1]),1))
    else:
        new_component = [set(cords[0]), set(cords[1]),1]
        for component_index in matching_components:
            component_to_join = components.pop(component_index)
            new_component[0] = new_component[0].union(component_to_join[0])
            new_component[1] = new_component[1].union(component_to_join[1])
            new_component[2] += component_to_join[2]
        components.append(new_component)


print(len(components)-1)