View Compilation Error

0_0_22250973_2890.cpp: In function 'int main()':
0_0_22250973_2890.cpp:27:14: error: 'M' was not declared in this scope
         ll a[M],b[M];
              ^
0_0_22250973_2890.cpp:30:26: error: 'a' was not declared in this scope
           scanf("%I64d",&a[i]);/*我犯的一个不明显的小错误，a,b数组未赋初值，而且scanf?ldquo;%d）读入，结果，ab的数组中是非常奇怪的数，所以以后定义数组一定要初始?*/
                          ^
0_0_22250973_2890.cpp:32:26: error: 'b' was not declared in this scope
           scanf("%I64d",&b[i]);
                          ^
0_0_22250973_2890.cpp:33:12: error: 'a' was not declared in this scope
         a1=a[0];b1=b[0];
            ^
0_0_22250973_2890.cpp:33:20: error: 'b' was not declared in this scope
         a1=a[0];b1=b[0];
                    ^