C :

#include<stdio.h>
#include<string.h>
int a[100005];
char ch[10000];
int main()
{
    //freopen("in.txt","r",stdin);
    int n, i, j, l, t, t1, t2, s, min, max;
    scanf("%d", &n);
    getchar();
    min = 100010; max = -1;
    memset(a, 0, sizeof(a));
    while(n--)
    {
        gets(ch);
        l = strlen(ch);
        s = 0;
        for(i = 0; i < l; i++)
        {
            s = 0;
            while(ch[i]>='0'&&ch[i]<='9')
            {
                s *= 10;
                s += (ch[i]-'0');
                i++;
            }
            if(s>0)
            {
                if(s > max) max = s;
                if(s < min) min = s;
                a[s]++;
            }
        }
    }
    for(i = min; i <= max; i++)
    {
        if(a[i] == 2)
            t2 = i;
        else if(a[i] == 0)
            t1 = i;
    }
    printf("%d %d", t1, t2);

    return 0;
}

C++ :

#include<cstdio>
int a[100003];
int main()
{
    //freopen("1.txt", "r", stdin);
    int i, n, s = 0, t = 0, l = 0, min = 1000000;
    int duan, chong;
    scanf("%d", &n);
    while(~scanf("%d", &n))
    {
        if(n < min)min = n;
        a[n]++;
        l++;
    }
    for(i=0; i<l; i++){
        if(a[min+i] == 0)duan = min+i;
        if(a[min+i] == 2)chong = min+i;
    }
    printf("%d %d\n",duan, chong);
    return 0;
}