years_int = int(input("Input number of years: "))

if years_int < 0:
    print("Invalid input!")

population_current = 307357870
oneyear_sec = 365 * 24 * 60 * 60 # 1 year = 365 days = 8760 hours = 525600 minuntes = 31536000 seconds
births_year = float(oneyear_sec / 7) # A birth every 7 seconds results in 4505142 births per year
deaths_year = float(oneyear_sec / 13) # A death every 13 seconds results in 2425846 deaths per year
immigrants_year = float(oneyear_sec / 35) #A new immigrant every 35 seconds results in 901028 immigrants per year
change_year = births_year + immigrants_year - deaths_year #2980324 plus per year

population_est = population_current + ( years_int * change_year)

print("Estimated population in", years_int, "year(s) is: ", population_est)