>>504
ほらよ、とりあえず版だ。

#include <windows.h>
#include <stdio.h>
#include <conio.h>

typedef struct {
　char Beads[351];
　int NumberOfBeads;
} Necklace;

static int NextPoint(const int NumberOfBeads, int Point, const int Step)
{
　Point += Step;
　if(Point < 0){
　　return Point + NumberOfBeads;
　}
　if(NumberOfBeads <= Point){
　　return Point - NumberOfBeads;
　}
　return Point;
}