#include <iostream>

#include <cstring>

#include <cstdio>

using namespace std;

const int maxn = 1e5 + 1e3;

char s1[maxn],s2[maxn];

int main()

{

    while(~scanf("%s%s",s1,s2))

    {

        int flag = 1;

        int len1 = strlen(s1);

        int len2 = strlen(s2);

        int cnt = 0;

        char change_ch1[5];

        char change_ch2[5];

        if(len1 != len2)flag = 0;

        for(int i = 0;i < len1 && flag ;++i)

        {

            if(s1[i] != s2[i])

            {

                change_ch1[++cnt] = s1[i];

                change_ch2[cnt] = s2[i];

            }

            if(cnt > 2)flag = 0;

        }

        if(cnt == 1)flag = 0;

        if(cnt == 2 && change_ch1[1] == change_ch2[2] && change_ch1[2] == change_ch2[1])

            flag = 1;

        else

            flag = 0;

        if(flag)

            printf("YES\n");

        else

            printf("NO\n");

    }

    return 0;

}