View Compilation Error

0_0_37005844_6499.cpp: In function 'long long int dfs(long long int)':
0_0_37005844_6499.cpp:54:16: error: 'inf' was not declared in this scope
         ret = -inf;
                ^
0_0_37005844_6499.cpp:56:15: error: 'inf' was not declared in this scope
         ret = inf;
               ^