#include <stdio.h>
int main(void) {
// your code goes here
int a,b,c,d,max;
scanf("%d,%d,%d,%d",&a
,&b
,&c
,&d
); if(a>=b&&a>=c&&a>=d)max=a;
if(b>=a&&b>=c&&b>=d)max=b;
if(c>=a&&c>=b&&c>=d)max=c;
if(d>=a&&d>=b&&d>=c)max=d;
return 0;
}
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