View Compilation Error

0_0_17030304_26633.cpp:18:8: error: 'MAX' was not declared in this scope
 char s[MAX];
        ^
0_0_17030304_26633.cpp:19:9: error: 'MAX' was not declared in this scope
 char ss[MAX];
         ^
0_0_17030304_26633.cpp: In function 'int main()':
0_0_17030304_26633.cpp:35:24: error: 's' was not declared in this scope
             scanf("%s",s);
                        ^
0_0_17030304_26633.cpp:49:34: error: 'ss' was not declared in this scope
             for(int i=0;i<n;i++) ss[i]='7';
                                  ^
0_0_17030304_26633.cpp:50:34: error: 'ss' was not declared in this scope
             for(int i=0;i<n;i++) ss[i+n]='4';
                                  ^
0_0_17030304_26633.cpp:51:13: error: 'ss' was not declared in this scope
             ss[len]=0;
             ^