Using ifelse for changing columns in R

I would like to apply the ifelse condition to the following data frame according to the schema. I can do it repeatedly, but I have a lot of data.

My code:

d <- data.frame(x_1 = sample(1:100,10),x_2 = sample(1:100,10), y_1 =sample(1:100,10), y_2 =sample(1:100,10), 
                 y_3 =sample(1:100,10), y_4 =sample(1:100,10))
ifelse(d$x_1>d$y_1, 0, d$x_1-d$y_1)
ifelse(d$x_2>d$y_2, 0, d$x_2-d$y_2)
ifelse(d$x_1>d$y_3, 0, d$x_1-d$y_3)
ifelse(d$x_2>d$y_4, 0, d$x_2-d$y_4) # x_1>y_5..., x_2>y_6,...