foo.cc: In function 'int main()':
foo.cc:84:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(j=0;j<s.size();j++){
            ~^~~~~~~~~
foo.cc:140:23: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
     if(gu[j][k]^may[j]==1){
                 ~~~~~~^~~
foo.cc:144:28: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
     else if(gu[j][k]^may[j]==0){
                      ~~~~~~^~~

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