View Compilation Error

0_0_17002133_20804.cpp: In function 'int main()':
0_0_17002133_20804.cpp:35:13: error: 'i' was not declared in this scope
         for(i = 1; i <= maxn; i ++)
             ^
0_0_17002133_20804.cpp:37:17: error: 'j' was not declared in this scope
             for(j = 0; j <= i; j ++)
                 ^
0_0_17002133_20804.cpp:46:9: error: 'ans' was not declared in this scope
         ans = 0;
         ^
0_0_17002133_20804.cpp:47:13: error: 'j' was not declared in this scope
         for(j = 0; j <= maxn + 1; j ++)
             ^