arr1 = list()
arr2 = list()
arr1 = input()
arr2 = input()
n = 0
if (len(arr1) == len (arr2)):
    if (arr1 == arr2):
        print(0)
    else:
        k = len(arr1)-1
        while (k > 0):
            if (arr1[k:]==arr2[k:]):
                n = (len(arr1)-k)*2
            else:
                k = k-1
        print(n)


elif (len(arr1) > len(arr2)):
    k = len(arr1)-len(arr2)
    arr1 = arr1[k:]
    n = k
    if (arr1 == arr2):
        print(n)
    else:
        k = len(arr1)-1
        while (k > 0):
            if (arr1[k:]==arr2[k:]):
                n = (len(arr1)-k)*2
            else:
                k = k-1
        print(n)


elif (len(arr1) < len(arr2)):
    k = len(arr2)-len(arr1)
    arr2 = arr2[k:]
    n = k
    if (arr1 == arr2):
        print(n)
    else:
        k = len(arr1)-1
        while (k > 0):
            if (arr1[k:]==arr2[k:]):
                n = (len(arr1)-k)*2
            else:
                k = k-1
        print(n)