from decimal import *
V,T,P = map(Decimal, input().split())

l = 0
r = (P+1)*V*T+1
for _ in range(500):
    x = (l+r)/2
    if (P+1)*V*T+T-1 < x*(T-1):
        r = x
    else:
        l = x
ans = int(r)
if ans%T == 0:
    ans -= 1
print(ans)