View Compilation Error

0_0_7634361_25714.cpp: In function `void dfs(int, int, int, int)':
0_0_7634361_25714.cpp:22: error: `ans' undeclared (first use this function)
0_0_7634361_25714.cpp:22: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7634361_25714.cpp:25: error: `i' undeclared (first use this function)
0_0_7634361_25714.cpp: In function `int main()':
0_0_7634361_25714.cpp:37: error: `i' undeclared (first use this function)