View Compilation Error

0_0_29919920_31699.cpp:3:11: error: '::main' must return 'int'
 void main()
           ^
0_0_29919920_31699.cpp: In function 'int main()':
0_0_29919920_31699.cpp:15:13: error: 'strlen' was not declared in this scope
   l=strlen(s);
             ^