#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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