#include <stdio.h>
int main() {
int countSchool;
scanf("%d", &countSchool);
int schoolBall[1000];
for (int i = 0; i < countSchool; i++)
scanf("%d", &schoolBall[i]);
int errSchoolBall[1000], errCountSchool = 0, middleBall = -1;
for (int i = 0; i < countSchool; i++) {
if (schoolBall[i] % 3 != 0) {
errSchoolBall[i] = 1;
if(middleBall == -1) middleBall = 0;
middleBall += schoolBall[i];
} else {
errCountSchool++;
errSchoolBall[i] = -1;
}
}
printf("%d\n", errCountSchool);
for (int i = 0; i < countSchool; i++)
if (errSchoolBall[i] == -1)
printf("%d ", i);
if(middleBall == -1) {
printf("\n0 0");
} else {
int countMiddleBall = 0;
middleBall = middleBall / (countSchool - errCountSchool);
for (int i = 0; i < countSchool; i++)
if(schoolBall[i] % 3 != 0 && schoolBall[i] == middleBall)
countMiddleBall++;
printf("\n%d %d", middleBall, countMiddleBall);
}
}
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