#include<stdio.h>
#include<math.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); 
 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;
}
   long long fac(int n) 
{   
    static long long p=1;   
      p = p*n;  
    return p;
 }

#include<stdio.h>
int func(int, int);
int main() 
{    
int k=4,m=1,p1,p2;
    p1 = func(k,m);     
    p2 = func(k,m) ;
    printf("%d,%d\n",p1,p2);
    return 0;
    }
int func(int a,int b) 
{  
 static int m=0,i=2;
 i += m+1;
m = i+a+b;
return (m);
}

#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)
{
    int i;
    if(n==0)
    i=0;
    else
    i=2*fun(n-1)+1;    
    return i;
}
 

#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);  // 函式呼叫 
    printf("\n");
    }        
    return 0;
    } 
void draw(int n,char symbol) 
{
    int i,line;
    for(line=1;line<=n;line++)
    {
      for(i=1;i<=n-line;i++){
      printf(" ");
}    
 for(i=1;i<=(2*line-1);i++)
 {
    printf("%c",symbol);
 }
 printf("\n");
 }
}