def calc(M, A, B) :
    k = M//A
    return (M-k)+k*B
A, B, C = list(map(int, input().split()))
ok, ng = 1000000000000000010, 0
while ok - ng > 1 :
    m = (ok+ng)//2
    if calc(m, A, B) >= C :
        ok = m;
    else:
        ng = m;
print(ok)