View Compilation Error

0_0_29168569_7775.cpp:6:9: error: 'maxn' was not declared in this scope
 char s1[maxn],s2[maxn],ans[maxn];
         ^
0_0_29168569_7775.cpp:6:18: error: 'maxn' was not declared in this scope
 char s1[maxn],s2[maxn],ans[maxn];
                  ^
0_0_29168569_7775.cpp:6:28: error: 'maxn' was not declared in this scope
 char s1[maxn],s2[maxn],ans[maxn];
                            ^
0_0_29168569_7775.cpp: In function 'int main()':
0_0_29168569_7775.cpp:29:17: error: 's1' was not declared in this scope
   scanf("%s %s",s1,s2);
                 ^
0_0_29168569_7775.cpp:29:20: error: 's2' was not declared in this scope
   scanf("%s %s",s1,s2);
                    ^