Why case 3 in a switch not executing ?

#include <stdio.h>
#include <stdlib.h>
#define MEAN(a,b) (float)(a+b)/2#define ABS(n) (n>0?n:n*-1)
#define TOLOWER(x) (x+32)
int main()
{

    int i,a,b,j;
    char k;
    printf("Enter 1 for MEAN\n2 for ABS\n3 for TOLOWER\n");
    scanf("%d",&i);
    switch(i)
    {
        case 1: printf("Enter a nd b\n");
                scanf("%d %d",&a,&b);
                printf("%f\n",MEAN(a,b));
                break;
        case 2: printf("Enter a no to find abs\n");
                scanf("%d",&j);
                printf("%d\n",ABS(j));
                break;
        case 3: printf("Enter upper to lower\n");

                scanf("\n%c",&k);      //add a new line here '\n'

                printf("%c", TOLOWER(k));
                break;
        default: printf("Hey wat u dng ? Its a wrong input\n");
                break;
    }
    return 0;
}