#include <stdio.h>
#include <string.h>
int main()
{
int n , m , cnt;
char str[10000];
for (int i = 0; str[i] != '\0'; i++)
{
if( str[i] == '4' || str[i] == '7' )
{
cnt++;
}
}
//printf("%d\n" , cnt);
if( cnt == 4 || cnt == 7)
{
}
else
{
}
return 0;
}
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