根据阶梯水费计算应交水费

#include <stdio.h>
int main()
{
float n,s;
printf(“输入用水量:”);
scanf("%f",&n);
if(n>=0&&n<=4)
s=1.5n;
else if(n>4&&n<=9)
s=1.9n;
else
s=2.1*n;
printf(“应交水费为%f\n”,s);
}