编写简单程序举行选举

模拟n个人参加选举的过程，并输出结果。设候选人有4个，用ABCD表示，选人时输入编号1234对应ABCD，没投给ABCD的为无效票。结束后按票数高低输出编号和所得票数

#include<stdio.h>
int main() {
    int a[4];
    int b[4] = {0, 1, 2, 3}
    int who;
    while (scanf("%d", &who) {
        who++;
    }

    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < i; j++) {
            if (a[i] > a[j]) {
                int temp = a[i];
                a[i] = a[j];
                a[j] = temp;

                int temp = b[i];
                b[i] = b[j];
                b[j] = temp;
            }
        }
    }

    for (int i = 0; i < 4; i++) {
        printf("%d:%d\n", b[i], b[j]);
    }
}

能说一下具体输入输出要求吗