import sequtils,strutils
var
    N, K, ans, n : int64
(N, K) = stdin.readline.split.map(parseBiggestInt)
for i in 0 .. (200000):
    for j in 0 .. min(i,K):
        var
            x = i - j
        if (i and x) == N and i >= x:
            ans += 1
if K > N:
    echo "INF"
else:
    echo ans