/in/foo.c:1:1: warning: data definition has no type or storage class
 a,b,c,d = map(int,input().split())
 ^
/in/foo.c:1:1: warning: type defaults to 'int' in declaration of 'a' [-Wimplicit-int]
/in/foo.c:1:3: warning: type defaults to 'int' in declaration of 'b' [-Wimplicit-int]
 a,b,c,d = map(int,input().split())
   ^
/in/foo.c:1:5: warning: type defaults to 'int' in declaration of 'c' [-Wimplicit-int]
 a,b,c,d = map(int,input().split())
     ^
/in/foo.c:1:7: warning: type defaults to 'int' in declaration of 'd' [-Wimplicit-int]
 a,b,c,d = map(int,input().split())
       ^
/in/foo.c:1:11: warning: implicit declaration of function 'map' [-Wimplicit-function-declaration]
 a,b,c,d = map(int,input().split())
           ^~~
/in/foo.c:1:15: error: expected expression before 'int'
 a,b,c,d = map(int,input().split())
               ^~~
/in/foo.c:2:1: error: expected ',' or ';' before 'x'
 x = a-c
 ^