View Compilation Error

0_0_18756772_16626.cpp: In function 'int main()':
0_0_18756772_16626.cpp:17:12: error: 'i' was not declared in this scope
     if (ch[i]=='x' && ch[i*j]=='r' && ch[i*j*j]=='y')
            ^
0_0_18756772_16626.cpp:17:28: error: 'j' was not declared in this scope
     if (ch[i]=='x' && ch[i*j]=='r' && ch[i*j*j]=='y')
                            ^