View Compilation Error

0_0_29334637_21658.cpp: In function 'int main()':
0_0_29334637_21658.cpp:19:10: error: 'S' was not declared in this scope
  else if(S[I]=='c')
          ^
0_0_29334637_21658.cpp:19:12: error: 'I' was not declared in this scope
  else if(S[I]=='c')
            ^