v,t,p=map(int,input().split())


#条件
def is_ok(time):
    return (p+1)*v + (time-1)//t<time


def meguru_bisect(ng,ok):
    while abs(ng-ok)>1:
        mid=(ng+ok)//2
        if is_ok(mid):
            ok=mid
        else:
            ng=mid
    return ok

print(meguru_bisect(0,10**50))