help me fix this

#include <stdio.h>
#define THIRTY_TWO 32 
#define ONE_POINT_EIGHT 1.8

int main()
{
	
float f,c, cal;
char ui;	
printf("This program converts Degree celsius to Fahrenheit and vice versa\n");
printf("Enter 'F' to convert F-C / Enter 'C' to convert C-F");
scanf("%c", ui);

if(ui == 'F' || 'f')
{
	printf("Enter the temp that is to be converted to Degree celsius:");
	scanf("%f", &f);
	cal = (f-THIRTY_TWO/ONE_POINT_EIGHT);
	printf("Temp is: %f°", &cal);
}
	if(ui == 'C' || 'c')
{
	printf("Enter the temp that is to be converted to Fahrenheit:");
	scanf("%f", &c);
	cal = ((c*ONE_POINT_EIGHT)+THIRTY_TWO);
	printf("Output is: %f°F", &cal);
}
	else()
	{	
		printf("Please enter a valid value");
		return 0;
	}
}