def check(x):
    return x <= (p+1)*v + (x+t-1)//t

v,t,p = map(int,input().split())
ok = 0
ng = 3*10**18
while ng-ok > 1:
    mid = (ok+ng)//2
    if check(mid):
        ok = mid
    else:
        ng = mid
print(ok)