openjudge 20:计算2的幂

描述
给定非负整数n，求2n。

输入
一个整数n。0 <= n < 31。
输出
一个整数，即2的n次方。
样例输入
3
样例输出
8


#include
#include
using namespace std;
int main()
{
    int n,a=1;
    cin>>n;
    for (i=1,i<=n,i++)
    {
        a*=2
    };
    cout<return 0;
}

错误信息如下

/home/runner/temp/35942998.6489/Main.cc: In function ‘int main()’:
/home/runner/temp/35942998.6489/Main.cc:7:2: error: ‘cin’ was not declared in this scope
    7 |  cin>>n;
      |  ^~~
/home/runner/temp/35942998.6489/Main.cc:3:1: note: ‘std::cin’ is defined in header ‘’; did you forget to ‘#include ’?
    2 | #include
  +++ |+#include 
    3 | using namespace std;
/home/runner/temp/35942998.6489/Main.cc:8:7: error: ‘i’ was not declared in this scope
    8 |  for (i=1,i<=n,i++)
      |       ^
/home/runner/temp/35942998.6489/Main.cc:12:2: error: ‘cout’ was not declared in this scope
   12 |  cout</home/runner/temp/35942998.6489/Main.cc:12:2: note: ‘std::cout’ is defined in header ‘’; did you forget to ‘#include ’?
/home/runner/temp/35942998.6489/Main.cc:12:9: error: expected ‘)’ before ‘;’ token
   12 |  cout</home/runner/temp/35942998.6489/Main.cc:8:6: note: to match this ‘(’
    8 |  for (i=1,i<=n,i++)

显示Compile Error
有人看看这是错哪了？

#include <iostream>
using namespace std;

第9行，for(int i=1;i<=n;i++)
11行，a*=2; 末尾要加分号