View Compilation Error

0_0_29168637_16299.cpp: In function 'int main()':
0_0_29168637_16299.cpp:39:15: error: 's' was not declared in this scope
   for(int i=0;s[i]!=0;++i) abit[s1[i]-'0']++,bbit[s2[i]-'0']++,len++;
               ^