r - Add a specific value of x-axis on ggplot -

i using ggplot function plot kind of graph image

i want add specific value of x-axis shown in picture

this code :

    quantiles <- quantile(mat,prob = quant)     x <- as.vector(mat)     d <- as.data.frame(x=x)     p <- ggplot(data = d,aes(x=x)) + theme_bw() +       geom_histogram(aes(y = ..density..), binwidth=0.001,color="black",fill="white") +       geom_density(aes(x=x, y = ..density..),fill="blue", alpha=0.5, color = 'black')      x.dens <- density(x)     df.dens <- data.frame(x = x.dens$x, y = x.dens$y)     p <- p + geom_area(data = subset(df.dens, x <= quantiles), aes(x=x,y=y),                        fill = 'green', alpha=0.6)     print(p)