P7909分糖果，老早之前的代码了，当时刚学完二分，然后上去就打还A了后面才了解到这玩意是道数学题

所以有没有大佬 hack 一下或者为什么这玩意正确么

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

long n, l, r, mid, ans, sum;
int main() {
    scanf("%d %d %d", &n, &l, &r);
    while (l <= r) {
        mid = (l + r) >> 1, sum = mid % n;
        if (sum >= ans) {
            ans = sum;
            l = mid + 1;
        } else r = mid - 1;
    }
    printf("%d\n", ans);
    return 0;
}