a,b,c=eval(input().replace(' ',','))
def func(x):
if x==0:
return a
if x==1:
return b
return func(x-1)+func(x-2)
print(func(c))
1706A - Another String Minimization Problem | 1695B - Circle Game |
1702B - Polycarp Writes a String from Memory | 1701A - Grass Field |
489C - Given Length and Sum of Digits | 886B - Vlad and Cafes |
915A - Garden | 356A - Knight Tournament |
1330A - Dreamoon and Ranking Collection | 1692B - All Distinct |
1156C - Match Points | 1675A - Food for Animals |
1328C - Ternary XOR | 1689A - Lex String |
1708B - Difference of GCDs | 863A - Quasi-palindrome |
1478A - Nezzar and Colorful Balls | 1581B - Diameter of Graph |
404A - Valera and X | 908A - New Year and Counting Cards |
146A - Lucky Ticket | 1594C - Make Them Equal |
1676A - Lucky | 1700B - Palindromic Numbers |
702C - Cellular Network | 1672C - Unequal Array |
1706C - Qpwoeirut And The City | 1697A - Parkway Walk |
1505B - DMCA | 478B - Random Teams |