Hill Cipher

#include <iostream>
#include <string>
#include <math.h>
using namespace std;
int main()
{
    char plaintext[3];
    int key[3][3];
    cout<<"Enter the elements for the key(integers only):"<<endl;
    for(int i=0;i<3;i++)
        for(int j=0;j<3;j++)
            cin>>key[i][j];
    cout<<"The entered key is :"<<endl;
    for(int i=0;i<3;i++)
    {
        cout<<"\n";
        for(int j=0;j<3;j++)
            cout<<key[i][j]<<" ";
    }
    cout<<"\n";
    cout<<"Enter a three letter word:"<<endl;
    cin>>plaintext;
    int message[3][1];
    for(int k=0;k<3;k++)
        for(int j=0;j<1;j++)
            message[k][j]=((int)plaintext[k]-97);
    cout<<"The message matrix is:"<<endl;
    for(int i=0;i<3;i++)
    {
        cout<<"\n";
        for(int j=0;j<1;j++)
            cout<<message[i][j];
    }
    cout<<"\n";
    cout<<"The multiplied matrix is:"<<endl;
    int k,i,j;
    int c[3][1];
    for(i=0;i<3;++i)
    {
        for(j=0;j<1;++j)
        {
            c[i][j]=0;
            for(k=0;k<3;++k)
                c[i][j]=c[i][j]+(key[i][k]*message[k][j]);
            cout<<c[i][j]<<" ";
        }
        cout<<"\n";
	}
    cout<<"The encrypted data is:"<<endl;
    for(int i=0;i<1;i++)
    {
    	cout<<"\n";
        for(int j=0;j<3;j++)
            cout<<(char)((fmod(c[i][j],26)+97));
    }
    cout<<"\n";
    float det=0;
    float ikey[3][3];
    for(i = 0; i < 3; i++)
        det=det + (key[0][i] * (key[1][(i+1)%3] * key[2][(i+2)%3] - key[1][(i+2)%3] * key[2][(i+1)%3]));
    cout<<"Inverse of matrix is:"<<endl;
    for(i = 0; i < 3; i++){
        for(j = 0; j < 3; j++)
        {
            cout<<((key[(j+1)%3][(i+1)%3] * key[(j+2)%3][(i+2)%3]) - (key[(j+1)%3][(i+2)%3] * key[(j+2)%3][(i+1)%3]))/det<<"\t";
            ikey[i][j]=((key[(j+1)%3][(i+1)%3] * key[(j+2)%3][(i+2)%3]) - (key[(j+1)%3][(i+2)%3] * key[(j+2)%3][(i+1)%3]))/det;
        }
        cout<<"\n";
    }
    float decrypt[3][1];
    for(i=0;i<3;i++)
    {
        for(j=0;j<1;j++)
        {
            decrypt[i][j]=0;
            for(k=0;k<3;k++)
                decrypt[i][j]=decrypt[i][j]+(ikey[i][k]*c[k][j]);
            cout<<decrypt[i][j]<<" ";
        }
        cout<<"\n";
    }
    cout<<"The decrypted data is:"<<endl;
    for(i=0;i<3;i++)
        cout<<(char)(fmod(decrypt[i][0],26)+97);
}