#include <stdio.h>
#include <string.h>
void rev(char s[]){
for(int i
=0,j
=strlen(s
)-1;i
<j
;i
++,j
--){ char t
=s
[i
]; s
[i
]=s
[j
]; s
[j
]=t
; } }
int main(){
char s[100];
rev(s);
}
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