foo.c: In function 'main':
foo.c:4:15: error: expected ')' before '<' token
    4 |      int x1(x1<1000000);
      |               ^
      |               )
foo.c:5:15: error: expected ')' before '<' token
    5 |      int x2(x2<1000000);
      |               ^
      |               )
foo.c:6:21: error: 'x1' undeclared (first use in this function)
    6 |      scanf("%d %d",&x1,&x2);
      |                     ^~
foo.c:6:21: note: each undeclared identifier is reported only once for each function it appears in
foo.c:6:25: error: 'x2' undeclared (first use in this function)
    6 |      scanf("%d %d",&x1,&x2);
      |                         ^~
foo.c:9:10: warning: unused variable 'y3' [-Wunused-variable]
    9 |      int y3=x1%x2;
      |          ^~
foo.c:8:10: warning: unused variable 'y2' [-Wunused-variable]
    8 |      int y2=x1*x2;
      |          ^~
foo.c:7:10: warning: unused variable 'y1' [-Wunused-variable]
    7 |      int y1=x1+x2;
      |          ^~

[Hydro](https://hydro.ac)提供评测服务