View Compilation Error

0_0_19186833_13043.cpp:3:11: error: '::main' must return 'int'
 void main()
           ^
0_0_19186833_13043.cpp: In function 'int main()':
0_0_19186833_13043.cpp:8:33: error: 'd' was not declared in this scope
     l=sqrt[(x-a)*(x-a)+(y-b)*(y-d)];
                                 ^