Bamboozled by long long

[arijitg@uci.edu]

 I have the following 2 lines in a program

 unsigned long long k=1;
 unsigned int i = 4;

 printf("The values are i: %d, , k: %lX, i+k: %lX \n", i,k , i+k);
 k = k + i;
 printf("The values are i: %d, , k: %lX, i+k: %lX \n", i,k , i+k);

I get the foll. outputs:

The values are i: 4, , k: 0, i+k: 1
The values are i: 4, , k: 0, i+k: 5

Note that (i+k) is showing k's current value, yet k is always showing 
0.

Any idea please?