View Compilation Error

0_0_39763966_21364.cpp: In function 'long double dis(long double, long double, long double, long double)':
0_0_39763966_21364.cpp:49:16: error: 'sqrt' was not declared in this scope
   49 |         return sqrt((x2-x1)*(x2-x1)*1.0+(y2-y1)*(y2-y1)*1.0);
      |                ^~~~