#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;
}

#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;
}

#include<stdio.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("%f,%lf",&x,&y);
    printf("%f,%lf\n",x,y); 
    
    return 0;
}

#include<stdio.h>
int main(){
    char x;
    x = getchar();
    
    if(x>'0'&&x<'9')
        printf("%c是数字字符\n",x);
    else if((x>'A'&&x<'Z')||(x>'a'&&x<'z'))
        printf("%c是英文字母\n",x);
    else
        printf("%c是其它字符\n",x);
        
    return 0;
}

#include<stdio.h>
int main(){
    char ans1,ans2;
    printf("复习了没？(输入y或Y表示复习了，输入n或N表示没复习):");
    ans1 = getchar();
    getchar();
    printf("动手敲代码了没?(入y或Y表示敲了，输入n或N表示没敲):");
    ans2 = getchar();
    
    if((ans1=='y'||ans1=='Y')&&(ans2=='y'||ans2=='Y'))
        printf("\n罗马不是一天建成的:)\n");
    else
        printf("\n罗马不是一天毁灭的。。。\n");
        
    return 0;
}

#include<stdio.h>
#include<math.h>
int main(){
    int q = 2, a1 = 2;
    int n,sum;
    scanf("%d",&n);
    sum = a1 * (1 - pow(q,n))/(1 - q) + 1;
    printf("n = %dʱ, sum = %d\n",n,sum);
    return 0;
}