#include <stdio.h>
#define WIN16 true
int main(void){
    #ifdef WIN16
        printf("The value of sizeof(int) is 2.\n");
    #else
        printf("The value of sizeof(int) is 4.\n");
    #endif
    return 0;
}

#include <stdio.h>
#define R 1
int main(){
    float len, area_round, area_square;
    printf ("input a number: ");
    scanf("%f", &len);
    #if R
        area_round = 3.14159*len*len;
        printf("Area of round is: %f\n", area_round);
    #else
        area_square = len*len;
        printf("Area of square is: %f\n", area_square);
    #endif
    return 0;
}