UVa 10062 - Tell me the frequencies!

// UVa 10062 - Tell me the frequencies!

#include <stdio.h>
#include <map>
#include <vector>
#include <algorithm>
#include <string>
#include <iostream>
using namespace std;

#define ch unsigned char

struct pa {
	char c;
	int f;
};

bool operator <(pa a, pa b) {
	return a.f < b.f || (a.f == b.f && a.c > b.c);
}

int main() {
	string s;
	int t = 0;
	while (getline(cin, s)) {
		t++;
		map<ch, int> m;
		for (int i = 0; i < s.length(); i++)
			m[s[i]]++;
		vector<pa> v;
		for (ch c = 32; c <= 128; c++)
			if (m[c] != 0) {
				pa p = { c, m[c] };
				v.push_back(p);
			}

		sort(v.begin(), v.end());
		if (t > 1)
			cout << endl;
		for (int i = 0; i < v.size(); i++)
			printf("%d %d\n", v[i].c, v[i].f);
	}
	return 0;
}