C++ Program to multiply two matrix.

#include<iostream.h>
#include<conio.h>
void main()
{clrscr();
int i,j,k,m1,n1,m2,n2,a[20][20],b[20][20],c[20][20];
cout<<"enter rows and columns of matrix 1";
cin>>r1>>c1;
cout<<"\n enter rows and columns of matrix 2";
cin>>r2>>c2;
if(n1==m2)                                                            

{
cout<<"Enter  first matrix ";
for(i=0;i<r1;i++)
 for(j=0;j<c1;j++)
   cin>>a[i][j];
cout<<"\n Enter second matrix";
for(i=0;i<m2;i++)
 for(j=0;j<n2;j++)
   cin>>b[i][j];
for(i=0;i<r2;i++)
{
 for(j=0;j<c2;j++)
  {c[i][j]=0;
   for(k=0;k<c1;k++)
    {c[i][j]+=a[i][k]*b[k][j];}                           //remember this 
    }
     }
for(i=0;i<m1;i++)
 {for(j=0;j<n2;j++)
  cout<<c[i][j]<<" ";
  cout<<"\n";
  }
  }
  else
  cout<<"\n sorry wrong entry  ABORTING!!!!";


 getch();
 }