C Program to print a half pyramid using a number

/* C Program to print a half pyramid using number */ 
#include <stdio.h>

void main() {

    int a, b, rows;

    printf("Enter number of rows:\t");
    scanf("%d", & rows);

    for (a = 1; a <= rows; a++) {
        for (b = 1; b <= a; b++) {
            printf("%d ", b);
        }
        printf("\n");
    }
}

Enter number of rows: 5
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

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Process exited after 1.456 seconds with return value 5
Press any key to continue . . .