import math

def tam_giac(a, b, c):
    if a + b > c and a + c > b and b + c > a:
        return True
    else:
        return False

def tinh_chu_vi(a, b, c):
    return a + b + c

def tinh_dien_tich(a, b, c):
    s = (a + b + c) / 2
    return math.sqrt(s * (s - a) * (s - b) * (s - c))

a = float(input("nhap so thu nhat : "))
b = float(input("nhap so thu hai : "))
c = float(input("nhap so thu ba : "))

if tam_giac(a, b, c):
    chu_vi = tinh_chu_vi(a, b, c)
    dien_tich = tinh_dien_tichn(a, b, c)
    print("3 so da cho la 3 canh cua tam giac .")
    print("chu vi : ", chu_vi)
    print("dien tich : ", dien_tich)
else:
    print("cac so da nhap khong phai 3 canh cua tam giac .")