func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long a, b, t, tt, i;     long long t1, t2, t3, t4;     while (~scanf( %lld %lld , &a, &b)) {       t = b - a;       t1 = a % 10;       t2 = b % 10;       t3 = (a / 10) % 10;       t4 = (b / 10) % 10;       if (t >= 10 || (t4 != t3)) {         printf( 0 n );       } else {         if (t1 <= 2 && t2 >= 5)           printf( 0 n );         else {           tt = 1;           for (i = t1 + 1; i <= t2; i++) {             tt *= i;           }           printf( %lld n , tt % 10);         }       }     }     return 0;   }   