View Compilation Error

0_0_13269796_14590.c: In function 'main':
0_0_13269796_14590.c:5:2: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
  for(int i=1;i<=31;i++)
  ^
0_0_13269796_14590.c:5:2: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_13269796_14590.c:7:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int j=1;j<=i;j++)
   ^
0_0_13269796_14590.c:22:3: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
   for(int i=1;i<=n;i++)
   ^
0_0_13269796_14590.c:25:4: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
    for(int j=1;j<=i;j++)
    ^