c012: 10062 - Tell me the frequencies!

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

typedef struct _node{

    int ascii;

    int count;

} Node;

bool compare (Node a,Node b){

    if (a.count == b.count) return b.ascii < a.ascii;

    else return a.count < b.count;

}

int main ()

{

    string s;

    int first=1;

    while (getline(cin,s)){

        if (first == 1){

            first=0;

        }else {

            cout << endl;

        }

        int c[257]={0};

        Node mynode[257];

        for(int i=0;i<s.length();i++){

            c[s[i]]++;

        }

        int k=0;

        for(int i=0;i<257;i++){

            if (c[i]>0){

                mynode[k].ascii=i;

                mynode[k].count=c[i];

                k++;

            }

        }

        sort(mynode,mynode+k,compare);

        for(int i=0;i<k;i++)

            cout << mynode[i].ascii << " "<<mynode[i].count <<endl;

    }

}