/in/ex2.c: In function 'sum':
/in/ex2.c:3:5: error: type of 'x0' defaults to 'int' [-Werror=implicit-int]
 int sum(x0,x1,x2,x3,x4,x){
     ^~~
/in/ex2.c:3:5: error: type of 'x1' defaults to 'int' [-Werror=implicit-int]
/in/ex2.c:3:5: error: type of 'x2' defaults to 'int' [-Werror=implicit-int]
/in/ex2.c:3:5: error: type of 'x3' defaults to 'int' [-Werror=implicit-int]
/in/ex2.c:3:5: error: type of 'x4' defaults to 'int' [-Werror=implicit-int]
/in/ex2.c:3:5: error: type of 'x' defaults to 'int' [-Werror=implicit-int]
cc1: all warnings being treated as errors