10252.cpp

#include <cstdio>
#include <cstring>

using namespace std;

int main(void)
{
    int  i, index, cnt[2][26];
    char arr[10000];

    while (gets(arr) != NULL) {
        for (i = 0; i < 26; ++i)
            cnt[0][i] = 0;
        for (i = 0; i < strlen(arr); ++i) {
            index = (int)(arr[i] - 'a');
            if (-1 < index && index < 26) cnt[0][index]++;
        }
        gets(arr);
        for (i = 0; i < 26; ++i)
            cnt[1][i] = 0;
        for (i = 0; i < strlen(arr); ++i) {
            index = (int)(arr[i] - 'a');
            if (-1 < index && index < 26) cnt[1][index]++;
        }
        for (i = 0; i < 26; ++i)
            cnt[0][i] = cnt[0][i] < cnt[1][i] ? cnt[0][i] : cnt[1][i];
        for (index = 0; index < 26; ++index)
            for (i = 0; i < cnt[0][index]; ++i)
                printf("%c", (char)(index + 'a'));
        printf("\n");
    }

    return 0;
}