View Compilation Error

0_0_29445886_9894.cpp:2:10: error: expected primary-expression before 'double'
 int main{double a;while(scanf("%lf",&a)!=EOF)printf("%lf\n",a>=0?a:-a);}
          ^
0_0_29445886_9894.cpp:2:10: error: expected '}' before 'double'
0_0_29445886_9894.cpp:2:10: error: expected ',' or ';' before 'double'
0_0_29445886_9894.cpp:2:19: error: expected unqualified-id before 'while'
 int main{double a;while(scanf("%lf",&a)!=EOF)printf("%lf\n",a>=0?a:-a);}
                   ^
0_0_29445886_9894.cpp:2:72: error: expected declaration before '}' token
 int main{double a;while(scanf("%lf",&a)!=EOF)printf("%lf\n",a>=0?a:-a);}
                                                                        ^