#include <stdio.h>
#include <stdint.h>
 
 struct s1{
     uint8_t u1;
     uint32_t u2; 
 };
 
 #pragma pack(1)
 
  struct s2{
     uint8_t u1;
     uint32_t u2; 
 };
 
int main(){
    int s_s1 = sizeof(struct s1);
    int s_s2 = sizeof(struct s2);
    
    printf("sizeof (s1) = %d\n", s_s1);
    printf("sizeof (s2) = %d", s_s2);
    
    return 0;
}