foo.c: In function 'main':
foo.c:7:16: warning: comparison of constant '91' with boolean expression is always true [-Wbool-compare]
    7 |         if(64<a<91)
      |                ^
foo.c:7:14: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
    7 |         if(64<a<91)
      |            ~~^~
foo.c:13:24: warning: comparison of constant '123' with boolean expression is always true [-Wbool-compare]
   13 |                 if(96<a<123)
      |                        ^
foo.c:13:22: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
   13 |                 if(96<a<123)
      |                    ~~^~
foo.c:5:20: warning: unused variable 'd' [-Wunused-variable]
    5 |         char a,b,c,d;
      |                    ^
foo.c:5:18: warning: unused variable 'c' [-Wunused-variable]
    5 |         char a,b,c,d;
      |                  ^
foo.c:5:16: warning: unused variable 'b' [-Wunused-variable]
    5 |         char a,b,c,d;
      |                ^

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