#include <cstdio>
#include <map>
std:: map <int, int> a;
int n, m, q, i, x, ans;
void solve(){
    scanf("%d", &n);
    for(i = 0 ; i < n ; i ++) scanf("%d", &x), a[x] ++;
    scanf("%d", &m);
    for(i = 0 ; i < m ; i ++){
        scanf("%d", &q);
        if(a[q]) ans ++;
    }
    printf("%d", ans);
}
int main(){
    solve();
}

#include <cstdio>
#include <algorithm>
int a[15051];
int n, m, q, i;
int ans;
int binary(){
    int left = 0, right = n-1, middle;
    while(left <= right){
        middle = (left + right) >> 1;
        if(a[middle] == q) return middle;
        if(a[middle] > q) right = middle - 1;
        if(a[middle] < q) left = middle + 1;
    }
    return -1;
}
void solve(){
    scanf("%d", &n);
    for(i = 0 ; i < n ; i ++) scanf("%d", a + i);
    std:: sort(a, a + n);
    scanf("%d", &m);
    while(m --){
        scanf("%d", &q);
        if(binary() != -1) ans ++;
    }
    printf("%d", ans);
}
int main(){
    solve();
}

Me too use the STL, its a simple and easy for write) And not more to time of run. 1.450 for map && 1.405 for binary_search..