我这哪错了？

#include<iostream>
using namespace std;
struct time{
	int s1,s2,c;
};
void in(time & a,time & b,int & sum);
int main()
{
	int n,sum=0;
	cin>>n;
	time a[n+5]={{0,0,0}};
	for(int i=1;i<=n;i++)in(a[i],a[i-1],sum);
	cout<<sum;
	return 0;
}
void in(time & a,time & b,int & sum)
{
	cin>>a.s1>>a.s2;
	a.c=a.s1+a.s2-8+b.c;
	sum+=a.c;
}