题解 | 小红的合数寻找

def sushu(x):
    if x < 2:
        return False
    for i in range(2,int(x**0.5)+1):
        if x%i == 0:
            return False
    return True

ls = [] 
x = int(input())
for i in range(x,2*x+1):
    if (i > 1) and not (sushu(i)):
        ls.append(i)
if len(ls) == 0:
    print(-1)
else:
    print(ls[0])