View Compilation Error

1_867_3612_24596.cpp: In function 'int main()':
1_867_3612_24596.cpp:31:17: error: 's' was not declared in this scope
    if(hour==12&&s[i+4]=='A')
                 ^
1_867_3612_24596.cpp:33:17: error: 's' was not declared in this scope
    if(hour==12&&s[i+4]=='P')
                 ^