c++ homework, task2

#include <stdio.h>
#include <cmath>
#include <iostream>
using namespace std;
int main()
{
     int a,b,i=0,dob=1,y=0,x=0,in,min,max1,max2,in1,in2;
     cout<<"vvedite dovzenu masiv 1"<<endl;
     cin>>a;
     int M1_VAR[a];
     cout<<"vvidete dovzinu massiv 2"<<endl;
     cin>>b;
     int M2_VAR[b];
     cout<<"first massiv"<<endl;
     while(i<a)
     {
         cin>>M1_VAR[i];
          min=M1_VAR[i];
          max1=M1_VAR[i];
         i++;
     }
     cout<<"second massive"<<endl;
     i=0;
     while(i<b)
     {
         cin>>M2_VAR[i];
         max2=M2_VAR[i];
         i++;
     }
     for(;y<b;y++)
     {
        if(y<6){
            dob=dob*M2_VAR[y];
        }
        if(M2_VAR[y]>=max2)
        {
            max2=M2_VAR[y];
            in2=y;
        }
     }
     for(x=0;x<a;x++)
     {
         if(M1_VAR[x]<=min){
             min=M1_VAR[x];
             in=x;
         }
         if(M1_VAR[x]>=max1)
        {
            max1=M1_VAR[x];
            in1=x;
        }
     }
     cout<<"dob first six= "<<dob<<endl;
     cout<<"min chislo= "<<min<<" index = "<<in<<endl;
     cout<<"max chislo 1 massiv= "<<max1<<" index= "<<in1<<endl;
     cout<<"max chislo 2 massiv= "<<max2<<" index= "<<in2<<endl;

    return 0;
}