函数怎么改？

#include<bits/stdc++.h>
using namespace std;
struct node
{
    int id;
    int c, m, e;
    int sum;
}a[301];
bool cmp(node x, node y)
{
    return x.sum < y.sum;
    if(x.sum == y.sum)
        return x.id < y.id;
}
int main()
{
    int n;
    scanf("%d", &n);
    for(int i = 1; i <= n; i ++)
    {
        scanf("%d%d%d", &a[i].c, &a[i].m, &a[i].e);
        a[i].id = i;
        a[i].sum = a[i].c + a[i].m + a[i].e;
    }
    sort(a + 1, a + n + 1, cmp);
    for(int i = n; i > n - 5; i --)
        cout << a[i].id << " " << a[i].sum << "\n";
    return 0;
}