/in/foo.c: In function 'main':
/in/foo.c:13:25: error: 'else' without a previous 'if'
   13 |                         else{ a[i][j]=a[i-1][j]=+a[i-1][j-1];
      |                         ^~~~
/in/foo.c: At top level:
/in/foo.c:23:1: error: expected identifier or '(' before 'return'
   23 | return 0;
      | ^~~~~~
/in/foo.c:24:1: error: expected identifier or '(' before '}' token
   24 | }
      | ^