24. Jolly Jumpers

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#define MAX 101

int main(void) {
    int N = 0;
    int input[MAX] = {0};
    int jumpers[MAX] = {0};
    
    scanf("%d", &N);
    
    for (int i = 0; i < N; i++) {
        scanf("%d", &input[i]);
    }
    
    for (int i = 0; i < N - 1; i++) {
        int min = abs(input[i] - input[i + 1]);
        
        if (min >= N) {
            printf("NO\n");
            return 0;
        }
        
        if (jumpers[min] == 0) {
            jumpers[min] = 1;
        } else {
            printf("NO\n");
            return 0;
        }
    }
    
    printf("YES\n");
    
    return 0;
}