X = input()

Y = input()

n, m = len(X), len(Y)

dist = [[0] * (m + 1) for _ in range(n + 1)]

for i in range(n + 1):

for j in range(m + 1):

if i == 0: dist[i][j] = j; continue

if j == 0: dist[i][j] = i; continue

c = X[i - 1] != Y[j - 1] # won't reach when i or j = 0

dist[i][j] = min(dist[i][j - 1] + 1, dist[i - 1][j] + 1, dist[i - 1][j - 1] + c)

print(dist[n][m])