n = int(input().strip())
if n <= 1:
    print(1)
    raise SystemExit
prev1 = 1
prev2 = 1
for i in range(2, n+1):
    fib = prev2 + prev1
    prev2, prev1 = prev1, fib
print(fib) n = int(input().strip()) n int(input().strip()) int input().strip() ().strip () input strip if n <= 1:
    print(1)
    raise SystemExit n <= 1 n 1 print(1) print 1 raise SystemExit SystemExit prev1 = 1 prev1 1 prev2 = 1 prev2 1 for i in range(2, n+1):
    fib = prev2 + prev1
    prev2, prev1 = prev1, fib i range(2, n+1) range 2 n+1 n 1 fib = prev2 + prev1 fib prev2 + prev1 prev2 prev1 prev2, prev1 = prev1, fib prev2 prev1 prev1 fib print(fib) print fib prev2, prev1 = prev1, fib prev1 prev2 prev1 = 1 1 prev1 n = int(input().strip()) int(input().strip()) n prev2 = 1 1 prev2 prev1 = prev1, fib fib prev1 fib = prev2 + prev1 prev2 + prev1 fib
n = int(input().strip())
if n <= 1:
    print(1)
    raise SystemExit
prev1 = 1
prev2 = 1
for i in range(2, n+1):
    fib = prev2 + prev1
    prev2, prev1 = prev1, fib
print(fib)