Answer Happy

Can you please tell me why it does not run? I get no errors but
when i try to run it it just has the restart program location line
every time. Any help is appreciated.
def get_prin_amt():
prin_amt = int(input('Please enter valid principal amount'))
if prin_amt >=0:
# Return the valid principal
return prin_amt()
else:
print('Please enter valid principal')
return get_prin_amt()
def get_prd():
prd = int(input('Please enter valid time period in months'))
if prd >=0 and prd <=48:
return prd
else:
print('Please enter valid time period')
return get_prd()
def get_int_rate():
int_rate = int(input('Please enter valid interest rate'))
#Data validation
if int_rate >=0 and int_rate >=16:
#return valid interest rate
return int_rate
else:
print('Please enter valid interest rate')
return int_rate
def get_loanCoast(principal, period, int_rate):
payment = (int_rate/(1-(1+int_rate)**(prd)))*prin
loanCoast = prin - prd * payment
return payment, loanCost
print('For loan 1')
prin,prd,int_rate =0,0,0
prin = get_prin_amt()
prd = get_prd()
int_rate = get_int_rate()
payment1,cost1 = get_loanCost(prin_amt, prd, int_rate)
#Function to calculate cost
print('Loan 1 payment = {}'.format(payment1))
#Print payment and cost of loan 1
print('Loan 1 Cost = {}'.format(cost1))
print('Loan 2')
prin = get_prin_amt()
prd = get_prd()
int_rate = get_int_rate
payment2,cost2 = get_loanCost(prin, prd, int_rate)
print('Loan 2 payment = {}'.format(cost2))
print('Sum of Cost of two loans = {}'.format(cost1 + cost2))