foo.c: In function 'main':
foo.c:5:8: error: expected expression before '%' token
  scanf(%d%d%d%d,&a&b&c&d)
        ^
foo.c:6:5: error: expected ';' before 'printf'
     printf("%d"，a+b+c+d);
     ^~~~~~
foo.c:6:16: error: stray '\357' in program
     printf("%d"，a+b+c+d);
                ^
foo.c:6:17: error: stray '\274' in program
     printf("%d"，a+b+c+d);
                 ^
foo.c:6:18: error: stray '\214' in program
     printf("%d"，a+b+c+d);
                  ^
foo.c:7:2: warning: implicit declaration of function 'system' [-Wimplicit-function-declaration]
  system("pause");
  ^~~~~~
foo.c:4:12: warning: unused variable 'd' [-Wunused-variable]
 {int a,b,c,d;
            ^
foo.c:4:10: warning: unused variable 'c' [-Wunused-variable]
 {int a,b,c,d;
          ^
foo.c:4:8: warning: unused variable 'b' [-Wunused-variable]
 {int a,b,c,d;
        ^
foo.c:4:6: warning: unused variable 'a' [-Wunused-variable]
 {int a,b,c,d;
      ^

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