View Compilation Error

0_0_18446102_32395.cpp: In function 'void dfs(int, long long int, long long int)':
0_0_18446102_32395.cpp:19:15: error: 'clock' was not declared in this scope
     if((clock()-c)/CLOCKS_PER_SEC > 0.02) return;
               ^
0_0_18446102_32395.cpp:19:20: error: 'CLOCKS_PER_SEC' was not declared in this scope
     if((clock()-c)/CLOCKS_PER_SEC > 0.02) return;
                    ^
0_0_18446102_32395.cpp: In function 'int main()':
0_0_18446102_32395.cpp:70:19: error: 'clock' was not declared in this scope
         sst=clock();
                   ^