View Compilation Error

0_0_38644362_289.cpp: In function 'int main()':
0_0_38644362_289.cpp:9:9: error: 'sqrt' was not declared in this scope
   dis = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
         ^~~~
0_0_38644362_289.cpp:9:9: note: suggested alternative: 'qsort'
   dis = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
         ^~~~
         qsort