#include <stdio.h>

main() { 
	int num ; 
	int sum = 0 ; 
	int i ; 

	printf( "Enter summation number: ") ; 
	scanf( "%d", &num) ; 

	for( i = num; i > 0; i--) { 
		sum = sum + i ; 
	}

	printf( "Summation is %d\n", sum) ; 
}