dalao看一看，我这出了啥错误？全WA。

#include<bits/stdc++.h>
using namespace std;
void fa(){
    int a, b;
    cin >> a >> b;
    cout << a + b << endl; 
}
void fb(){
    char s[1000005];
    cin >> s;
    int ans = 0;
    for (int i = 0; i < strlen(s); ++i)
        if (s[i] == 'a')
            ++ans;
    cout << ans << endl;
}
void fc(){
    int n,a[1000],b[1000];
    cin >> n;
    for (int i = 0; i < n; ++i) cin >> a[i];
    for (int i = 0; i < n; ++i) {
        b[i] = a[i + 1] - a[i];
        if (i + 1 == n)b[i] = a[0] - a[i];
    }
    for (int i=0;i<n;++i)cout<<b[i]<<"\n"[i==(n-1)];
}
int main(){
    fa();fb();fc();
}
```、