View Compilation Error

0_0_35418389_20439.cpp: In function 'int main()':
0_0_35418389_20439.cpp:26:37: error: 'c' was not declared in this scope
   if(!((s[0]>='a' && s[0]<='z') || (c>='A' && c<='Z') || s[0]=='_'))
                                     ^