Three Strings - C++

Given N string values, the program must print 3 string values as the output as described in the Example Input/Output section. 

Input format: The first line will contain N denoting the number of string values. Next N lines will contain the N string values. 

Output format: Three lines containing string values as described in the Example Input/Output section. 

Example Input/Output 1: 

Input: 
3 
JOHN 
JOHNY 
JANARDHAN 

Output: 
JJOJAN 
OHHARD 
NNYHAN 

Example Input/Output 2: 
Input: 
4 
JOHN 
JOHNY 
JANARDHAN 
MIKESPENCER 

Output: 
JJOJANMIKE 
OHHARDSPE 
NNYHANNCER

Source Code:

#include <iostream>

#include<string>

using namespace std;

int main(int argc, char** argv)

{

int n,i,j;

cin>>n;

string s,a,b,c;

for(i=0;i<n;i++)

{

    cin>>s;

    a+=s.substr(0,i+1);

    b+=s.substr(i+1,s.length()-2*(i+1));

    c+=s.substr(s.length()-(i+1));

}

cout<<a<<"\n"<<b<<"\n"<<c;

}