CompileError!

main.c: In function \xe2\x80\x98main\xe2\x80\x99:\nmain.c:4:5: error: expected \xe2\x80\x98,\xe2\x80\x99 or \xe2\x80\x98;\xe2\x80\x99 before \xe2\x80\x98double\xe2\x80\x99\n    4 |     double r;\n      |     ^~~~~~\nmain.c:5:18: error: \xe2\x80\x98r\xe2\x80\x99 undeclared (first use in this function)\n    5 |     scanf("%lf",&r);\n      |                  ^\nmain.c:5:18: note: each undeclared identifier is reported only once for each function it appears in\n