[ASK] Java

can anyone tell me how to use nextInt() ? i totally dont understand even the easiest probelm.

The code should look like this.

      import java.io.*;
      import java.util.*;
      public class zi
      {
          StreamTokenizer in;
          PrintWriter out;
       
            int nextInt() throws IOException{
               in.nextToken();
               return (int)in.nval;
            }
       
            void run() throws IOException{
               in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
               out = new PrintWriter(new OutputStreamWriter(System.out));
               solve();
            }

          void solve()throws IOException{
              int a = nextInt();
	      //here it is
          }

         public static void main(String[] args)throws IOException{
            new zi().run();
         }
      }

where I must put integer M = ... under the int a=nextInt() ?

The line

int a = nextInt();

is where you enter a value into variable "a".

So if you want to have a variable by the name "M" then write

int M = nextInt();