foo.c: In function 'main':
foo.c:4:18: error: stray '\303' in program
    4 |  int b1,a1,b2,a2,×1,×2,j,k,i;
      |                  ^
foo.c:4:19: error: stray '\227' in program
    4 |  int b1,a1,b2,a2,×1,×2,j,k,i;
      |                   ^
foo.c:4:20: error: expected identifier or '(' before numeric constant
    4 |  int b1,a1,b2,a2,×1,×2,j,k,i;
      |                    ^
foo.c:4:22: error: stray '\303' in program
    4 |  int b1,a1,b2,a2,×1,×2,j,k,i;
      |                      ^
foo.c:4:23: error: stray '\227' in program
    4 |  int b1,a1,b2,a2,×1,×2,j,k,i;
      |                       ^
foo.c:6:2: error: 'x1' undeclared (first use in this function); did you mean 'a1'?
    6 |  x1=a1*a2;
      |  ^~
      |  a1
foo.c:6:2: note: each undeclared identifier is reported only once for each function it appears in
foo.c:7:2: error: 'x2' undeclared (first use in this function); did you mean 'a2'?
    7 |  x2=b1*a2+a1*b2;
      |  ^~
      |  a2
foo.c:8:2: error: 'j' undeclared (first use in this function)
    8 |  j=x1;
      |  ^
foo.c:9:2: error: 'k' undeclared (first use in this function)
    9 |  k=x2;
      |  ^
foo.c:12:3: error: 'i' undeclared (first use in this function)
   12 |   i=x2%x1;
      |   ^
foo.c:5:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d%d\n%d%d" ,&b1,&a1,&b2,&a2);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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