View Compilation Error

0_0_16570227_9896.cpp: In function 'void dfs(int)':
0_0_16570227_9896.cpp:13:8: error: 'f' was not declared in this scope
     if(f==1)
        ^
0_0_16570227_9896.cpp:18:8: error: 'f' was not declared in this scope
     if(f==1)
        ^
0_0_16570227_9896.cpp:22:9: error: 'f' was not declared in this scope
         f=1;
         ^
0_0_16570227_9896.cpp: In function 'int main()':
0_0_16570227_9896.cpp:34:9: error: 'f' was not declared in this scope
         f=0,flag=0;
         ^
0_0_16570227_9896.cpp:34:13: error: 'flag' was not declared in this scope
         f=0,flag=0;
             ^