5 3
 1000 3
 777 17
 4 3
 2 2
 100 4
 10 4
 999 2
 6 4
 1 2
 17 3
 1 4
 26 8
 91 5
 1 3
 1000 2
 20 3
 9 4
 123 5
 1000 1000
 3 2
 3 3
 80 970
 1000 4
 1 1000

7
 1499
 825
 5
 3
 133
 13
 1997
 7
 1
 25
 1
 29
 113
 1
 1999
 29
 11
 153
 1001
 5
 4
 80
 1333
 1

X, Total = list(map(int, input().split())), 0
if X[1] > X[0]:
    print(X[0])
    exit()
Total, X[0] = Total + X[1], X[0] - X[1]
while X[0] // (X[1] - 1) >= 1:
    Total, X[0] = Total + X[1], X[0] - X[1] + 1
print(Total + X[0] + 1)

# UB_CodeForces
# Advice: Don't limit your challenge, challenge your limits
# Location: Behind my desk next my quince lemon tea
# Caption: It's beautiful day and I want to make it perfect
# CodeNumber: 455
