V,T,P=map(int,input().split())

def is_ok(time):
    return (P+1)*V+(time-1)//T<time

def meguru_bisect(ng,ok):
    while abs(ok-ng)>1:
        mid=(ok+ng)//2
        if is_ok(mid):
            ok=mid
        else:
            ng=mid
    return ok
ans=meguru_bisect(0,10**50)
print(ans)