a, b, t = map(int,input().split())
# a円の切手x枚, b円の切手y枚
y = 0
ans = []
#X = []
#Y = []

while True:
    x = (t - b * y) // a
    if (t - b * y) % a != 0:
        x += 1

    if x < 0 :
        break
    ans.append(a * x + b * y)
    #X.append(x)
    #Y.append(y)

    if  b * y > t :
        break

    y += 1
#print(X)
#print(Y)
#print(ans)
ans.sort()

print(ans[0])