Multimap

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    map<char,int>mp;
    map<char,int> :: iterator it;
    cin>>n;
    cin.ignore();
    string s,s1="";
    while(n--){
        getline(cin,s);
        for(int i=0 ; i<s.size() ; i++){
            if(isalpha(s[i])){
                s1+=toupper(s[i]);
            }
        }
    }
    for(int i=0 ; i<s1.size() ; i++){
        mp[s1[i]]++;
    }
    multimap<int, char, greater <int> > mp2;
    multimap<int, char, greater <int> > :: const_iterator it1;
    for(it=mp.begin() ; it!=mp.end() ; it++){
        mp2.insert(make_pair(it->second , it->first));
    }

    for(it1=mp2.begin() ; it1!=mp2.end() ; it1++){
       cout<<it1->second <<" " <<it1->first <<endl;
    }
    return 0;
}