import sys
from itertools import combinations, permutations, product, accumulate, groupby
from collections import defaultdict, deque, Counter
from functools import reduce
import heapq
import bisect
import math
import copy

sys.setrecursionlimit(10 ** 9)
input = lambda: sys.stdin.readline().rstrip()
INF = float("inf")
MOD = 10 ** 9 + 7
# DFS
# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')

V, T, P = map(int, input().split())
def is_ok(arg):
    # 条件を満たすかどうか？問題ごとに定義
    return (P + 1) * V + (arg - 1) // T < arg


def meguru_bisect(ng, ok):
    '''
    初期値のng,okを受け取り,is_okを満たす最小(最大)のokを返す
    まずis_okを定義すべし
    ng ok は  とり得る最小の値-1 とり得る最大の値+1
    最大最小が逆の場合はよしなにひっくり返す
    '''
    while (abs(ok - ng) > 1):
        mid = (ok + ng) // 2
        if is_ok(mid):
            ok = mid
        else:
            ng = mid
    return ok
print(meguru_bisect(0, 10**50))