#include <math.h> 
  #include <stdio.h>
   void solve(double a, double b, double c);
    int main() {
     double a, b, c; 
     printf("Enter a, b, c: "); 
     while(scanf("%lf%lf%lf", &a, &b, &c) != EOF) { 
     solve(a, b, c); 
     printf("Enter a, b, c: ");
      }
      
 
return 0;
       }
       void solve(double a, double b, double c) {
        double x1, x2; 
        double delta, real, imag;
        
         if(a == 0) 
         printf("not quadratic equation.\n");
          else {
          delta = b*b - 4*a*c; 
          
          if(delta >= 0) {
           x1 
 
= (-b + sqrt(delta)) / (2*a);
           x2 = (-b - sqrt(delta)) / (2*a); 
           printf("x1 = %f, x2 = %f\n", x1, x2);
 }
 else {real = -b/(2*a);
  imag = sqrt(-delta) / (2*a);
   printf("x1 = %f + %fi, x2 = %f - %fi\n", real, imag, real, imag); } 
   }
}

#include <stdio.h> 
long long fac(int
 
 n); // 函式宣告 
int main() {
 int i,n;
 
  printf("Enter n: ");
  
   scanf("%d", &n); 
   for(i=1; i<=n; ++i)
 printf("%d! = %lld\n", i, fac(i)); return 0;
  }// 函式定義 
  long long fac(int n) { 
  static long long p = 1; 
  p = p*n;
   return p;
}

#include <stdio.h>
 #define N 1000 
 int  fun(int n,int m,int bb[N]) {
  int i,j,k=0,flag; 
  for(j=n;j<=m;j++) {
  
   flag=1; 
  
  for(i=2;i<j;i++)
   if(j%i==0) { 
   flag=0; break; }
  if(flag==1) 
  bb[k++]=j; }
  return k;
 }
int main(){ 
 int n=0,m=0,i,k,bb[N];
  scanf("%d",&n); 
  scanf("%d",&m); 
  for(i=0;i<m-n;i++) 
  bb[i]=0;
   k=fun(   n,  m,  bb); 
   for(i=0;i<k;i++)
    printf("%4d",bb[i]);
     return 0;
}

#include <stdio.h> 
long long fun(int n); // 函式宣告 
int main()
 { int n;
  long long f;
   while(scanf("%d", &n) != EOF)
    { 
    f = fun(n); // 函式呼叫
     printf("n = %d, f = %lld\n", n, f);
      }
      return 0;
}
long long fun(int n){
    static int a=1,b=0;
    if(0<=n&&n<=32)
    for(b=1;b<n;b++){
    a=a*2;
    b=a+b;
    b=b-1;
}
   else 
   printf("errror\n");

return b;

#include <stdio.h> 
void draw(int n, char symbol); // 函式宣告 
#include <stdio.h> 
int main() {
 int n, symbol;
  while(scanf("%d %c", &n, &symbol) != EOF) {
   draw(n, symbol);

    printf("\n");
     }
     return 0;
      }
     void draw(int n,char symbol){
          int a,b;
          for(a=1;a<=n;a++){
              for(b=1;b<=n-a;b++){
    
                  printf(" ");
              }
                  for(b=1;b<=2*a-1;b++){
                      printf("%c",symbol);
                  
                  }
              
              printf("\n");
        
    }
    
    }