poj2808校门外的树

/*POJ2808 校门外的树 program2.3.cpp*/#include<cstdio>#include<cstring>const int maxlen = 10001;int main(void){    int m, n, l, k;    int a[maxlen];    while(scanf("%d%d", &m, &n) != EOF)    {        memset(a, 0, sizeof(a));        while(n--)        {            scanf("%d%d", &l, &k);            for(int i = l; i <= k; i++)            {                a[i] = 1;            }        }    }    int cnt = 0;    for(int j = 0; j <= m; j++)    {        if(a[j] == 0)            cnt++;    }    printf("%d\n", cnt);    return 0;}