题解 | #杨辉三角的变形#

#include <stdio.h>
#include <string.h>
int main() {
    int n;
    scanf("%d", &n);
    if (n <= 2)
        printf("-1\n");
    else {
        n = n - 2;
        int j = n % 4;
        switch (j) {
            case 1:
                printf("2\n");
                break;
            case 2:
                printf("3\n");
                break;
            case 3:
                printf("2\n");
                break;
            case 0:
                printf("4\n");
                break;
        }
    }
    return 0;
}