//ex1.cpp
#include<stdio.h>
int main(){
    int a=5,b=7,c=100,d,e,f;
    
    d=a/b*c;
    e=a*c/b;
    f=c/b*a;
    printf("d=%d,e=%d,f=%d\n",d,e,f);
    
    return 0;
}

//ex2.cpp
#include<stdio.h>
int main(){
    
    int x=1234;
    float f=123.456;
    double m=123.456;
    char ch='a';
    
 
char a[]="hello world!";
    int y=3,z=4;
    
    printf("%d %d\n", y , z);
    printf("y=%d,z=%d\n",y ,z);
    printf("%8d,%2d\n", x,x);
    printf("%f,%8f,%8.1f,%0.2f,%.2e\n",f,f,f,f,f);
    printf("%1f\n",m);
    printf("%3c\n",ch);
    printf("%s\n%15s\n%10.5s\n%2.5s\n%.3s\n",a,a,a,a,a);
    
    
 
return 0;
} 

// ex3.cpp

#include <stdio.h>
#include <stdlib.h>
int main() {
    double x,y;
    char c1,c2,c3;
    int a1,a2,a3;
    
    scanf("%d%d%d",&a1, &a2, &a3);
    printf("%d,%d,%d\n",a1,a2,a3);
    
    scanf("%c%c%c", &c1, &c2, &c3);
    printf("\'%c\'\'%c\'\'%c\'\n
 
",c1,c2,c3);
    
    scanf("%lf, %lf", &x, &y);
    printf("%.1lf, %.1lf\n", x, y);
    
    system("pause");
    
    return 0;
}

//ex4.cpp
#include<stdio.h>
int  main(){
    
    char x;

    x=getchar();

    if( x >= 48 && x <= 57 )
    printf("%c是數字字元", x);

    else if ( x >= 65 && x <= 90 )
    printf("%c是大寫字母字元",x);
  
    else if( x >= 97 && x <= 122 )
    printf("%c是小寫字母字元",x);
  
    else
    printf("%c是其他字元",x);
  
    return 0; 

}

//ex5.cpp
#include<stdio.h>
int main(){
    char ans1,ans2;
    
    printf("複習了沒？(輸入y或Y表示複習了，輸入n或N表示沒複習)：");
    ans1= getchar();
    
    getchar();
    
    printf("\n動手敲程式碼了沒？（輸入y或Y表示複習了，輸入n或N表示沒複習):");
    ans2=getchar();
    
     if((ans1=='y'||ans1=='Y') && (ans2=='y'||ans2=='Y'))
     printf("\n羅馬不是一天建成的\n:)");
    
    else
    printf("\n羅馬不是一天毀滅的\n");
    
    return 0;
}

#include<stdio.h>
#include<math.h>

int main(){
    int n,a1=1,q=2;
    double sum;
    
    scanf("%d",&n);
    
    sum = (a1*(1-pow(q,n)))/(1-q);
    printf("當n=%d時，,sum=%.0lf",n,sum);
    
    return 0;
    
    
}