using readf in D

[Carlos]

Hi guys! I'm writing a little program in D from another version I 
did for my homework written in C. But it doesn't work very well. 
First it takes two reads for the first input from the user and 
second it only calculates tcsleep.

Here is the code:

import std.stdio;
import std.c.stdlib;
void main()
{
immutable sitc = 1.66;
immutable sleepc = 1.08;
float tcsleep, tcsit, tc;
int minsleep, minsit;
write("Input number of minutes sleep : \n");
readf("%d ", &minsleep);

write("Input number of minutes sitting : \n");
readf("%d ", &minsit);

write("Thanks!\n");
tcsleep = minsit*sitc;
tcsit = minsleep*sleepc;
tc = tcsleep+tcsit;
writeln("Your total calories is : ", tc);
exit (0);
}