bjfu1252 贪心

/*
 * Author    : ben
 */
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <functional>
#include <numeric>
#include <cctype>
using namespace std;
const int MAXN = 210;
typedef struct Interval {
    int a, b;
    Interval(int aa = 0, int bb = 0) {
        a = aa;
        b = bb;
    }
} Interval;
inline bool operator<(const Interval &i1, const Interval &i2) {
    return i1.b < i2.b;
}
inline bool isCross(const Interval &i1, const Interval &i2) {
    if (i1.a == i2.a) {
        return true;
    }
    if (i1.a < i2.a) {
        return i1.b > i2.a;
    }
    return i2.b > i1.a;
}

Interval inte[MAXN], res[MAXN];

int main() {
    int n, a, b;
    while (scanf("%d", &n) == 1 && n > 0) {
        for (int i = 0; i < n; i++) {
            scanf("%d%d", &inte[i].a, &inte[i].b);
        }
        sort(inte, inte + n);
        int I = 0;
        res[I++] = inte[0];
        for (int i = 1; i < n; i++) {
            int j = 0;
            for (;j < I; j++) {
                if (isCross(inte[i], res[j])) {
                    break;
                }
            }
            if (j == I) {
                res[I++] = inte[i];
            }
        }
        printf("%d\n", I);
    }
    return 0;
}