$1,4,6,7$ 点 WA ， $5,8$ 点 MLE

#include"cstdio"
#define N 50005
int n,m,q;
int f[N];

int found(int x);

int main()
{
    for (int i=1;i<=N;++i)f[i]=i;
    scanf ("%d%d%d",&n,&m,&q);
    for (int i=1,x,y;i<=m;++i)
    {
        scanf ("%d%d",&x,&y);
        f[y]=x;
    }
    for (int i=1,x,y;i<=q;++i)
    {
        scanf ("%d%d",&x,&y);
        if (found(x)==found(y))
        {   printf("Yes\n");}
        else 
        {   printf("No\n");}
    }
}

int found(int x)
{
    if (f[x]==x)return x;
    return f[x]=found(f[x]);
}

请大佬帮个忙，帮我看看哪里错了，谢谢！