#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
); 	max=a;
	if(b>max) max=b;
	if(c>max) max=c;
	if(d>max) max=d;
	return 0;
}
 
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