刚入门c语言，能帮我看看可以吗

学校题目，研究一晚上了也没搞懂。循环也不知道怎么用，还有flag不知道怎么搞

#include <stdio.h>
int main()
{
    int n,count= 0;
    scanf("%d",&n);
    count += n/100;
    n=n%100;
    count+=n/50;
    n=n%50;
    count+=n/20;
    n=n%20;
    count+=n/10;
    n=n%10;
    count+=n/5;
    n=n%5;
    count+=n/2;
    n=n%2;
    if(n != 0)
        count++;
    printf("%d",count);
}