foo.c: In function 'main':
foo.c:16:12: warning: statement with no effect [-Wunused-value]
        a[i][j]
        ~~~~^~~
foo.c:17:6: error: expected ';' before '}' token
      }
      ^
foo.c:9:6: warning: unused variable 'cnt' [-Wunused-variable]
  int cnt=0;
      ^~~
foo.c:4:10: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  int n,m;scanf("%d%d",&n,&m);//n行m列 
          ^~~~~~~~~~~~~~~~~~~
foo.c:8:4: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d",&a[i][j]);
    ^~~~~~~~~~~~~~~~~~~~

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