View Compilation Error

0_0_13833687_32124.cpp: In function 'int main(int, char**)':
0_0_13833687_32124.cpp:37:10: error: 'j' was not declared in this scope
      if (j >= num) {
          ^
0_0_13833687_32124.cpp:42:9: error: 'i' was not declared in this scope
     if (i < str.size() - 1 - n)
         ^