Buggy python submission (verdict: Runtime Error):
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = calcM(A, B, N)

    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calcM(A, B, x))
    return maxM


def resolve_v3(A, B, N):
    maxM = calcM(A, B, N)
    if B < N:
        max_x = max(list(filter(lambda x: (x + 1) % B == 0, range(N-B, N+1))), default=N)
    # print('max_x:', max_x)
    return max(maxM, calcM(A, B, max_x))

if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v3(A, B, N)
    print(M)




Fixed submission:
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = calcM(A, B, N)

    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calcM(A, B, x))
    return maxM


def resolve_v3(A, B, N):
    maxM = calcM(A, B, N)

    k, r = divmod(N, B)
    if k and B * k -1 <= N:
        # k * B - 1で調査
        maxM = max(maxM, calcM(A, B, k * B - 1))
    # if r == 0:
    #     maxM = max(maxM, calcM(A, B, N - 1))

    maxM = calcM(A, B, min(N, B - 1))


    return maxM

if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v3(A, B, N)
    print(M)

Buggy python submission (verdict: Time Limit Exceeded):
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = calcM(A, B, N)

    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calcM(A, B, x))
    return maxM


def resolve_v3(A, B, N):
    maxM = calcM(A, B, N)
    max_x = max(list(filter(lambda x: (x + 1) % B == 0, range(N+1))), default=N)
    # print('max_x:', max_x)
    return max(maxM, calcM(A, B, max_x))

if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v3(A, B, N)
    print(M)




Fixed submission:
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = calcM(A, B, N)

    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calcM(A, B, x))
    return maxM


def resolve_v3(A, B, N):
    maxM = calcM(A, B, N)

    k, r = divmod(N, B)
    if k and B * k -1 <= N:
        # k * B - 1で調査
        maxM = max(maxM, calcM(A, B, k * B - 1))
    # if r == 0:
    #     maxM = max(maxM, calcM(A, B, N - 1))

    maxM = calcM(A, B, min(N, B - 1))


    return maxM

if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v3(A, B, N)
    print(M)

Buggy python submission (verdict: Time Limit Exceeded):
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = calcM(A, B, N)

    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calcM(A, B, x))
    return maxM


if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v2(A, B, N)
    print(M)




Fixed submission:
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = calcM(A, B, N)

    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calcM(A, B, x))
    return maxM


def resolve_v3(A, B, N):
    maxM = calcM(A, B, N)

    k, r = divmod(N, B)
    if k and B * k -1 <= N:
        # k * B - 1で調査
        maxM = max(maxM, calcM(A, B, k * B - 1))
    # if r == 0:
    #     maxM = max(maxM, calcM(A, B, N - 1))

    maxM = calcM(A, B, min(N, B - 1))


    return maxM

if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v3(A, B, N)
    print(M)

Buggy python submission (verdict: Time Limit Exceeded):
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = 0
    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calc(A, B, x))
    return maxM


if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v1(A, B, N)
    print(M)




Fixed submission:
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = calcM(A, B, N)

    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calcM(A, B, x))
    return maxM


def resolve_v3(A, B, N):
    maxM = calcM(A, B, N)

    k, r = divmod(N, B)
    if k and B * k -1 <= N:
        # k * B - 1で調査
        maxM = max(maxM, calcM(A, B, k * B - 1))
    # if r == 0:
    #     maxM = max(maxM, calcM(A, B, N - 1))

    maxM = calcM(A, B, min(N, B - 1))


    return maxM

if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v3(A, B, N)
    print(M)

Buggy python submission (verdict: Time Limit Exceeded):
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

# def resolve_v2(A, B, N):
#     if B < N:
#         return max(calcM(A, B, N+1), calcM(A, B, N))

if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v1(A, B, N)
    print(M)




Fixed submission:
# floor(Ax/B) - A floor(x/B) の最大値Mを求める
# xはN以下の非負整数
# floor(Ax / B) = M + A floor(x / B)
# x / B = k + r
# Ax / B = Ak + Ar

# floor(Ak + Ar) = M + A floor(k + r)
# Ak + floor(Ar) = M + Ak + A floor(r)
# floor(Ar) = M

# r = x / B - k
# M = floor(A * (x / B - k))
#   = floor(A * x /B) - Ak
#   = floor(A/B * x) - Ak
#   = floor(A/B * x) - A * (x // B) 

# A B N
# 5 7 4

# M = floor(5/7 * x) - 5 * (x // 7)


# A B N 
# 11 10 9
# M = floor(11 / 10 * x) - 11 * (x // 10)

import math

def calcM(A, B, x):
        return math.floor(A / B * x) - A * math.floor(x / B)    

def resolve_v1(A, B, N):
    maxM = 0
    for x in range(N+1): # O(N)
        M = calcM(A, B, x)
        maxM = max(maxM, M)

    return maxM

def resolve_v2(A, B, N):
    # x == kB - 1
    maxM = calcM(A, B, N)

    for x in filter(lambda x: (x + 1) % B == 0, range(N+1)): # O(N/B)
        maxM = max(maxM, calcM(A, B, x))
    return maxM


def resolve_v3(A, B, N):
    maxM = calcM(A, B, N)

    k, r = divmod(N, B)
    if k and B * k -1 <= N:
        # k * B - 1で調査
        maxM = max(maxM, calcM(A, B, k * B - 1))
    # if r == 0:
    #     maxM = max(maxM, calcM(A, B, N - 1))

    maxM = calcM(A, B, min(N, B - 1))


    return maxM

if __name__ == '__main__':
    A, B, N = map(int, input().split())
    M = resolve_v3(A, B, N)
    print(M)