foo.cc: In function 'int main()':
foo.cc:120:18: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
  120 |     for(int i=0;i<strlen(s);i++){
      |                 ~^~~~~~~~~~
foo.cc:121:20: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  121 |         if(s[i]>=97&&s[i]<=122||s[i]>=65&&s[i]<=90){
      |            ~~~~~~~~^~~~~~~~~~~
foo.cc:126:18: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
  126 |     for(int i=1;i<strlen(s);i++){
      |                 ~^~~~~~~~~~

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