pcs <- function(R){
  m <- length(R) 
  w <- runif(m)
  
  v <- rep(1,m)
  u <- rep(1,m)
  v[1] <- w[1]^(1/(1+R[m]))
  for(i in 2:m){
    sr <- sum(R[(m-i+1):m])
    v[i] <- w[i]^(1/(i+sr))
    # print(c(sr, w[i], v[i]))
  }
  
  u[1] <- 1-v[m]
  for(i in 2:m){
    u[i] <- 1-prod(v[(m-i+1):m])
  }
  u
}
# pcs(rep(1, 10))
