Smallest number you can get by adding up numbers in sequence
Python - 104 99

My interpretation:

L=map(int,input().split())
k=1
while k in map(sum,[[i,j]for i in L for j in L if i&lt;j]):k+=1
print k


I tested it with the input string 0 1 2 3 4 8 11 19 33 59 154 196 260 containing a 0 to avoid the trivial solution 0.

Result:

16