#!/usr/bin/env python3

n, k, p = input().split()
n, k = int(n), int(k)
p = float(p)

M = 1000

def binom(a, b):
    ans = 1
    for i in range(1, b+1): ans = ans * (a+1-i) // i
    return ans

# Compute probability of dying in turn i:
dk = [0]*M
# Probability of dying the latest in turn i:
cdk = [0] * M
# Probability that 1 dies in turn i and all others are already dead.
ans = 0
for i in range(1, M):
    dk[i] = binom(i-1, k-1) * (1-p)**k * p**(i-k)
    cdk[i] = cdk[i-1] + dk[i]
    ans += dk[i] * cdk[i-1]**(n-1)

print(1-n*ans)