foo.cc: In function 'int main()':
foo.cc:39:11: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
         if(str[i]<='Z'&&str[i]>='A')
           ^
foo.cc:43:11: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
         if(str[i]<='z'&&str[i]>='a')
           ^

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