n, m, k = map(int, input().split())
res = 1
if n+k-m < 0:
print(0)
else:
for i in range(k+1):
res *= 1.0*(m-k+i)/(n+1+i)
res = 1 - res;
print("{:.12f}".format(res))
1271A - Suits | 259B - Little Elephant and Magic Square |
1389A - LCM Problem | 778A - String Game |
1382A - Common Subsequence | 1512D - Corrupted Array |
667B - Coat of Anticubism | 284B - Cows and Poker Game |
1666D - Deletive Editing | 1433D - Districts Connection |
2B - The least round way | 1324A - Yet Another Tetris Problem |
246B - Increase and Decrease | 22E - Scheme |
1566A - Median Maximization | 1278A - Shuffle Hashing |
1666F - Fancy Stack | 1354A - Alarm Clock |
1543B - Customising the Track | 1337A - Ichihime and Triangle |
1366A - Shovels and Swords | 919A - Supermarket |
630C - Lucky Numbers | 1208B - Uniqueness |
1384A - Common Prefixes | 371A - K-Periodic Array |
1542A - Odd Set | 1567B - MEXor Mixup |
669A - Little Artem and Presents | 691B - s-palindrome |