代码如下：

#include<iostream>
#include<stack>
#include<string>
#include<cmath>
#include<iomanip>
#include<algorithm>
#include<climits>
#include<cstdio>
using namespace std;
long long n, m, a[2000001], c;
void r(long long& x)
{
	x = 0;
	char c = getchar();
	while ('0' <= c && c <= '9')
	{
		x = 10 * x + c - 48;
		c = getchar();
	}
}
void p(long long x)
{
	int b[10], l = 0;
	while (x)b[++l] = x % 10 + 48, x /= 10;
	++l;
	while (--l)putchar(b[l]);
	putchar('\n');
}
int main()
{
	r(n), r(m);
	for (long long i = 1; i <= n; ++i)
	{
		r(a[i]);
	}
	for (long long i = 1; i <= m; ++i)
	{
		r(c);
		p(a[c]);
	}
	return 0;
}

本地测样例是正确的，结果提交了就全错，用scanf,printf就能过