# find a missing number in a list
data = [3,8,1,9,4,10,6,7,2]
# 5 is missing; list is not sorted

# you can also transform a list to 
# a set to make the solution faster
# for bigger data arrays:

data = set(data)
for i in range(1,len(data)+1):
    # 1 ... 10
    if i not in data:
        print(f"{i} is missing")
        # done; it's found
        break

# Output:
# 5 is missing
