题解 | 完全数计算

#include<stdio.h>
int main() {
    int num;
    while (scanf("%d", &num) != EOF) {
        if (num < 6)
            printf("0\n");
        else if (num < 28) {
            printf("1\n");
        } else if (num < 496) {
            printf("2\n");
        } else if (num < 8128) {
            printf("3\n");
        } else
            printf("4\n");
    }
    return 0;
}